Cut the tofu block into cubes. Place in a single layer on a tray lined with a kitchen napkin. Cover with another napkin and place a saucepan on top. Leave for 15 minutes.
Toss the drained tofu with 1 tbsp cornstarch. Heat 1 tbsp peanut oil in a skillet and add the tofu. Cook for 4-5 minutes before turning the tofu pieces over.
Heat oil in the same skillet you used for tofu. Add the ginger and garlic. Cook for 10-15 seconds, stirring continuously. Add the onions, and bell peppers.