Cut the tofu into 1cm thick slices.
Slice the onion and green onion.
Heat cooking oil in a pan and pan-fry the tofu on both sides until golden brown.
Push the tofu to the side of the pan and sauté the onion.
Add gochujang, soy sauce, minced garlic, and water, then bring to a boil.
Spoon the sauce over the tofu and simmer on low heat until the sauce thickens.
Top with green onion to finish.