In any case, I trimmed and boiled green beans for 5 minutes or so until cooked but still crunchy. I immediately shocked them in ice water to make the color bright and to stop the cooking.
Dressing: I put the black sesame paste (3 tbs) in a small Japanese mortar or "suribachi" すり鉢 and added sugar (1 tsp), soy sauce (1 tsp) and mirin (2 tsp). Using a pestle "surikogi" 擂り粉木, I mixed it until a nice saucy consistency is reached.
I garnished it with roasted white sesame seeds. The taste is similar to white sesame paste but the visual effect is quite different. I served this with slices of miso-marinated tofu. This dish really depends on the quality of the green beans. Some green beans have tough skins and no matter how long you cook them, the skin remains tough and fibrous. This time, we were lucky. These beans were still crunchy but not fibrous at all and the black sesame dressing looked nice with great contrast to the red of tomato and white of tofu.