firm tofu drain to remove the water on the surface. Transfer to cutting board, flip on its side and slice in half lengthwise. Flip it back over to lay flat on the cutting board and cut into equal cubes. Cut red pepper and green pepper into small pieces.
In a medium bowl, combine the remaining 2 tbsp soy sauce, 2 tbsp water, 1 tablespoon cornstarch, vinegar, brown sugar. Whisk to combine. Set aside.
Heat 2 tablespoons oil in a large deep skillet or wok over medium heat. Carefully add the tofu. Fry the tofu for 8 minutes, flipping every minute or so to brown all sides. Transfer to a plate.
Add remaining 1 tbsp of oil to the pan, add the onion Sauté 30 seconds. then add ginger, garlic.
Increase heat to high and add the red pepper, green pepper and peanuts, dried red chili pepper and Cook 3 to 4 minutes, stirring until slightly cooked, then return the tofu and sauce.stirring often, to combine, for 2 to 4 minutes until thickened.
To serve and scallion greens on top and serve immediately.