Preheat a large skillet to medium-high heat with a drizzle of oil.
In a small dish, combine the soy sauce, rice vinegar, sugar, and dashi together until very well mixed.
When the skillet is very hot, add the peppers in one layer and let them sizzle and blister for 2 minutes. Flip the peppers, and let cook for one minute more with out disturbing, then pour half of the sauce into the skillet. Toss to coat the peppers, and turn the heat off the skillet.
Pour the peppers and sauce into a bowl. Pour over the rest of the dashi sauce and top with scallions and sesame seeds. Serve as an appetizer or side dish. Enjoy!