Press the tofu by wrapping it in a towel and placing a heavy object on top for 15-20 minutes.

Unwrap the tofu and cut it into 1-inch cubes; coat with cornstarch.

Heat vegetable oil in a skillet and fry the tofu cubes for 4-5 minutes on each side until golden brown and crispy.

Whisk together soy sauce, rice vinegar, brown sugar, ketchup, and sesame oil in a mixing bowl to make the sauce.

Sauté the bell pepper and pineapple in the same skillet for 3-4 minutes, then add the sauce and stir well.

Gently fold the crispy tofu into the skillet and cook for another 2-3 minutes until heated through.

Warm taco shells, fill with the tofu mixture, and top with cabbage and green onions before serving.