Boil First, Then Sear: "Mune-Toro Yaki" — Steps for Tender Chicken Breast, Plus Oil-Free "Endless Mushroom Natto"

The recipe uses one chicken breast weighing about 350g. Ryuji first cuts the meat in half, checks the direction of the grain, and then slices across it. The key, Ryuji says, is to angle the knife diagonally rather than cutting straight across. Cutting vertically is fine too, but by Ryuji's explanation, a diagonal cut severs the fibers more thoroughly, making the meat more tender. When the host remarked, "I don't see many cooks cutting chicken breast vertically," Ryuji replied that cutting it this way makes it turn out tender.

The pieces should be small enough to eat in one bite, but not too thin. Since the dish is meant to go with rice this time, the priority is keeping some heft to each bite. Ryuji believes there's huge demand for ways to cook chicken breast, so there can never be too many recipes.

The cut meat is seasoned with liquid shio koji. It's Ryuji's own product, and apparently it hadn't made many appearances this year. Ryuji explained that shio koji tenderizes meat and also adds umami. The amount is 1 tablespoon plus 1 teaspoon for 350g of meat. Because shio koji is salty, no salt is added; you can sprinkle some on later to taste. If you don't have liquid shio koji, you can substitute half a teaspoon of salt and 1 tablespoon of sake. That said, Ryuji recommends liquid shio koji, as it adds more flavor and tastes better.

The other ingredient that makes the meat tender is cornstarch. The host immediately thought of suishodori (crystal chicken). About 1 tablespoon plus 1 teaspoon of cornstarch is added and massaged in to coat the surface of the meat. Too much and it won't feel like a stir-fry, so keep the amount modest. The marinating time is 5 to 10 minutes. Ryuji says marinating longer doesn't make much difference, and made the side dish in the meantime.

The side dish uses 100g each of shimeji and king oyster mushrooms, about 200g in total. The king oyster mushrooms are cut in half and then torn, and the shimeji are halved and separated. They're made smaller than usual so they mix well with the natto and are easier to pick up with chopsticks. Ryuji prefaced this by saying the side dish is optional, explaining that since the main dish has no vegetables, the plan was to balance things out with mushrooms and natto. When the host said it "seems like a diet menu," Ryuji agreed. Ryuji also mentioned that it makes a fairly large amount, so it's good for meal prep, and that natto keeps reasonably well.

The only cooking method is stir-frying, because it's "the easiest." The mushrooms go into a cold frying pan, and the heat is turned on without any oil. Stir-frying draws out moisture and concentrates the mushrooms' umami, which alone makes them delicious once combined with natto. Oil isn't used because it adds calories. Whether to brown them is up to you; the goal is to drive off the moisture.

During cooking, moisture from the mushrooms evaporated with a "pssss" sound. Ryuji emphasized that this evaporation is important. Boiling adds unnecessary water, and the umami doesn't concentrate. Ryuji's view is that searing makes the mushrooms more flavorful and tasty than either boiling or microwaving.

To draw out even more moisture, two pinches of salt are added. According to Ryuji, adding salt breaks down the cell walls through osmotic pressure, releasing water. Even without oil, the mushrooms take on a glossy sheen and shrink down. Raising the temperature gradually from a cold pan also brings out the umami, Ryuji says. Pressing them with a spatula releases even more water. The host, tasting at this stage, was surprised at how concentrated the umami was with only salt. Ryuji said these mushrooms would also work as a side for the chicken.

Next, the natto is added. Two packs were used this time, but if you're eating alone, one pack is plenty, and half the mushrooms is fine too. The sauce packets from both packs go in as well. Ryuji says the bonito dashi in the sauce and the salt on the mushrooms are enough to make it delicious. Taste it and add a pinch of salt if needed, though it's fine without, Ryuji says. Ryuji also mentioned that finishing it with just bonito flakes and soy sauce is delicious too. The finished side dish goes into the refrigerator to chill for a while.

Though named "yaki" (seared), mune-toro yaki is boiled once before searing. Water is brought to a boil in a frying pan. Ryuji stressed, "Be sure to use a frying pan," not a pot, saying the reason would become clear later.

Once the water boils, the meat is added one piece at a time, keeping them apart. Putting them all in at once makes them stick together and not taste good, Ryuji says. In the hot water, the entire surface firms up, leaving the meat half-cooked. Ryuji explained this is the same principle as suishodori. The boiling time is very short, just under a minute, and the meat isn't cooked through at this point. When the host confirmed, "So that was just to coat it?", Ryuji said yes.

The boiled meat is lifted out, the frying pan is returned to the stove with a light coating of oil, and the meat is seared over high heat. Stir-frying in oil from the start gives a crispy finish, but boiling first leaves moisture on the surface, creating a silky, melting texture. Once searing begins, the cornstarch reacts and a solid golden-brown color forms quickly. The searing time is extremely short, and the host was surprised: "You're turning off the heat already?"

Ryuji replied that it's already cooked through. There's no red in the cross-section, and a slight hint of pink is when it's most tender, Ryuji says. When the host mentioned that commenters sometimes worry, "Is this really okay?", Ryuji answered, "Trust me." The residual heat continues cooking the meat while it's being seasoned.

Seasoning is done after turning off the heat. Black pepper is sprinkled evenly, and about 8 shakes of garlic powder are added and tossed. Black pepper alone is fine, but adding garlic powder makes it tastier, Ryuji says. To finish, sprinkle on Ajishio or salt. Using salt gives a lighter flavor. This is optional; Ryuji says it has plenty of flavor without it.

When the plated meat is lifted with chopsticks, it's so tender it slides right off. Ryuji described the tenderness as making you wonder whether chicken breast had a toro cut. However, Ryuji repeatedly explained that as a cooking method it's still a stir-fry: suishodori that's then been stir-fried. The Endless Mushroom Natto was finished with a sprinkle of green onions.

Eating it on hot rice, the host said "Definitely making this again" after the first bite, calling it healthy and very delicious. The host felt it might be tastier than making ordinary chicken ham, and Ryuji agreed. Ryuji also rated it the top among recent chicken breast recipes.

Ryuji says they've tried many times simply searing cornstarch-coated meat as is. Even so, Ryuji says boiling and then searing is "definitely" more delicious. By Ryuji's explanation, adding the searing step drives off surface moisture and concentrates the umami. The host has also made suishodori, and says that compared with various people's recipes, adding a sear is overwhelmingly better. Both said they had never seen anyone make suishodori by searing it.

Ryuji broke down the reason for the tenderness into two parts: the cornstarch coating keeps the meat's moisture from escaping, and the shio koji tenderizes the meat itself. Together, these create a texture like eating toro, Ryuji says. The host, who had briefly suspected it might be raw, confirmed that it's properly cooked and still tender.

The two said chicken breast tends to dry out, and many people probably don't know how to cook it well. Ryuji says anyone can make this recipe without failing. Just cook it to the same doneness, and even if you overcook it, it only gets a little tougher; it won't taste bad. That said, Ryuji rated this time's doneness as "the best of the best."

Both had independently thought Lemosco (a lemon-flavored hot sauce) would go well with it. After actually trying it, Ryuji said, "There's no way it wouldn't go well." Plain lemon is delicious too, Ryuji says.

Ryuji recommends it as a great recipe for people on a diet. It uses cornstarch, but not much. The host described the meat as shining golden, as if wearing a thin coating.

The host also touched on a recent trend on X. Perhaps because you can post four images at once, there has been an increase in posts rounding up Ryuji's recipes using healthy ingredients like chicken breast, saying "this one is delicious." From what the host has seen, it's especially women making these posts, and they get shared widely. So in the host's view, this recipe is also an eye-catching, "X-friendly" dish.

A bowl of rice was finished in no time. Ryuji said there had been an assumption that chicken breast doesn't go well with rice, but this one is light yet makes you want to keep eating rice.

As for the Endless Mushroom Natto, Ryuji says it takes little effort, so you could probably make it even on days when you lack motivation. After eating it, the host called it "a gentle flavor for your body" and said it's something they'd like to keep on hand. Ryuji says they really like the method of stir-frying to concentrate the mushrooms' moisture. The assessment is that, with no umami seasoning deliberately added, it's complete with just the umami of the mushrooms and the sauce.

Ryuji said that, being busy with daily video uploads and corporate sponsorships, this kind of meal is exactly what Ryuji wants right now. Rich Western food is nice too, but a meal with a good balance of protein and vegetables is better, Ryuji says. They also talked about how mune-toro yaki could go in a bento. As a variation, the host suggested adding ume (pickled plum), and Ryuji replied that it would probably go well.

On what inspired the recipe, Ryuji explained the following. Wanting to try the 7-Eleven "mune-yaki" that Yasumoto-san had recommended, Ryuji went to the store, only to find it had already been discontinued. So Ryuji wondered whether it could be made at home, and thought about how to achieve a toro-like texture. Ryuji's most tender chicken breast dish was suishodori, dusted with cornstarch and dipped in boiling water. But that alone would just be suishodori, so Ryuji tried searing it. That made it go really well with rice — that's how it came about.

When the host said, "In a way, it's thanks to Yasumoto-san," Ryuji laughed that Yasumoto-san's contribution was enormous. Ryuji regards Yasumoto-san as probably more knowledgeable than a mediocre cooking researcher. The two also talked about a future collaboration.

Finally, Ryuji reflected that this year marks the 9th or 10th year since starting cooking. After doing it this long, creating something new becomes difficult, but Ryuji says taking on challenges like this one is very important. Ryuji then said, "Cooking really is fun, there are always new discoveries," and wrapped up by calling it a recipe you'll definitely want to make again once you've tried it. The episode ended with talk about how the leftover natto can be arranged in various ways, such as by adding ume.