Cut the tofu into bite-sized pieces.
Chop the onion and green onion.
Place the tofu in a pan.
Put the chopped onion and green onion on top of the tofu.
Mix soy sauce, minced garlic, red pepper powder, and sesame oil to make a sauce.
Pour the sauce evenly over the tofu.
Cover with a lid and steam over medium-low heat for 10 minutes.