Press the firm tofu to remove excess moisture. Wrap in a towel and place a heavy object on top for 15–20 minutes.

Cut the pressed tofu into bite-sized cubes and toss with cornstarch until coated.

Heat vegetable oil in a skillet over medium heat. Fry the tofu for 7–10 minutes until golden brown.

Remove tofu, add bell pepper and pineapple to the skillet, and stir-fry for 3–5 minutes.

Whisk together soy sauce, rice vinegar, brown sugar, ketchup, and sesame oil in a bowl and pour over vegetables. Return tofu to skillet and cook for an additional 2–3 minutes.

Build tacos by filling shells with tofu and vegetable mixture. Top with cabbage and green onions.