Hiyayakko is a classic example of where you take 1 ingredient and you elevate it to something incredibly flavoursome. If you are looking for something different to eat, that is extremely easy to make then this would be excellent for you.
The only ingredient with enough calories worth tracking is the tofu. Feel free to use more or less of the other ingredients.
Tofu is a complete source of protein and is an excellent choice for vegetarians or vegans.