Dice the tofu and onion into cubes.
Drain the oil from the canned tuna.
Heat cooking oil in a pan and sauté the onions.
When the onions turn translucent, add the tofu and tuna and stir-fry.
Season with soy sauce, gochujang (Korean chili paste), and minced garlic.
Cook all ingredients evenly over medium heat.
Add green onion, stir-fry once more, and finish.