In a wok or cast iron skillet (do NOT use non-stick), heat the sesame oil over medium-high heat.
1 tsp toasted sesame oil
Add the peppers, and stir to toss in the sesame oil. Let the peppers sit and blister for a few minutes.
1 pound shishito peppers
Stir, and let sit again until they have reached your desired level of blistered. (3-5 minutes)
Add the soy sauce and stir to coat.
1/4 tsp soy sauce
Transfer peppers to a bowl, and sprinkle with sesame seeds and a pinch of kosher salt. Serve immediately.
pinch Kosher salt, sesame seeds
Notes
The key to getting an amazing blister without making the peppers soggy is to cook them fast and hot. You want a high temp and a very hot preheated wok/cast iron so they start cooking the second they hit the pan.