Cut the tofu and tuna into bite-sized pieces.
Slice the onion and green onion.
Heat cooking oil in a pan and grill the tofu on both sides until golden brown.
Place the grilled tofu in the pan, top with tuna, onion, and green onion.
Mix soy sauce, red pepper powder, minced garlic, and water to make the seasoning sauce.
Pour the sauce into the pan and bring to a boil.
Simmer over medium heat until the sauce reduces.