Cut the tofu, mushrooms, onion, and green onion into bite-sized pieces.
Heat cooking oil in a pan and sauté the onion and green onion.
Add the mushrooms and cook, then add the tofu.
Add gochujang, soy sauce, sugar, and minced garlic; mix well and stir-fry.
Pour in a little water and simmer until the flavors meld.
Serve the sautéed mixture over rice and finish with a sprinkle of sesame seeds.