In a small bowl, add ½ tbsp Japanese soy sauce (koikuchi shoyu), 1 tsp toasted white sesame seeds, 1 tsp Chinese-style chicken bouillon powder, 1 tsp sugar, 1 tsp rice vinegar and ½ tsp dashi granules. Mix and set by the stove for later. Cut 250 g green bell peppers into thin strips.
Heat a pan on medium-low and add ½ tbsp cooking oil. Once hot, add the peppers and fry for 1 minute.
Pour the prepared sauce into the pan and continue to stir-fry until the bell pepper is evenly coated and the excess liquid has evaporated.
Transfer the bell peppers to a heatproof mixing bowl and add 50 g canned tuna, ½ tbsp Japanese mayonnaise and ½ tbsp toasted sesame oil. Mix until evenly distributed.
Serve with a sprinkle of bonito flakes (katsuobushi) and ground black pepper. Enjoy!
Notes
Chicken bouillon powder varies by brand. My brand is 1 tsp per 200 ml, so if yours is more concentrated (e.g., 1 tsp per 300 ml), use less to avoid oversalting.