Rinse peppers well, dry them, and toss them with both kinds of oil.
Get a large cast iron skillet hot over medium high heat and add in all the peppers. Be sure to turn on the fan over your stove as it might get a little smokey.
Let peppers char for 2-3 minutes and stir once so they are charred on all sides.
When peppers are lightly charred all around, remove from pan and add to a bowl. Cover with plastic wrap and let steam for 2-3 minutes.
Drizzle peppers with soy sauce and plate. Cover with a liberal topping of sesame seeds and bonito flakes and serve with sriracha chili sauce.