Place tofu on a tea towel or paper towels. Cover with another towel and gently press tofu to get rid of excess water.
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 32 equal cubes.
Place in a medium size shallow container so the cubes can lay in an even layer.
In a small bowl, combine 2 tablespoons soy sauce with 2 tablespoons cornstarch. Whisk to combine and then pour over tofu. Gently flip cubes to make sure all sides are covered in marinade. Allow to sit while you make the sauce.
In a medium bowl, combine remaining 1/4 cup soy sauce, 1/2 cup water, remaining 1 tablespoon cornstarch, vinegar, sherry, brown sugar and Sambal (use 3 teaspoons if you like it really spicy*). Whisk to combine.
Heat 2 tablespoons sesame oil in a large deep skillet or wok over medium heat. Carefully add the tofu (the oil may splatter).
Fry the tofu for 8-10 minutes, flipping every minute or so to brown all sides. Transfer to a plate.
Add remaining teaspoon of sesame oil to the pan then the add ginger, garlic and scallion whites. Sauté 30 seconds.
Increase heat to high and add the zucchini and peppers. Cook 3 to 4 minutes, stirring until slightly cooked, then add the tofu and sauce.
Cook, stirring often, to combine, for 2 to 4 minutes until thickened.
To serve sprinkle peanuts and scallion greens on top and serve immediately.