Cut the chicken and tofu into bite-sized pieces and set aside.
Finely chop the onion, green onion, and garlic.
Heat cooking oil in a pan and sauté the garlic, onion, and green onion until fragrant.
Add the chicken and stir-fry until the outside is cooked.
Add the tofu and stir-fry together.
Season with soy sauce, gochujang (Korean chili paste), sugar, and pepper. Mix and stir-fry evenly.
Once all the ingredients are cooked through, turn off the heat and drizzle with sesame oil to finish.