Put the rice on to cook according to packet instructions.
Press as much water as you can from the tofu using a kitchen towel or a clean tea towel and cut it into small pieces. Add to a mixing bowl, sprinkle over the cornflour, salt, pepper and garlic powder and toss lightly to coat the tofu.
To a frying pan, heat 3-4 tablespoons of vegetable oil and lightly fry the tofu pieces, turning them until each piece is golden and crispy on each side. Once cooked, set aside on a plate lined with kitchen towel to absorb some of the excess oil.
In a jar or small bowl, combine the ingredients for the sticky sweet and sour sauce together except the water, and mix well. Once the sauce is smooth, add the water, stir and set aside.
Return the frying pan to a medium-high heat and add another tablespoon of vegetable oil. Fry the chunky onion pieces until softened and golden, about 5 minutes. Next add the pepper slices, and fry for a further 3-4 minutes. If you like your peppers soft, rather than crunchy, keep cooking them for an additional 3-4 minutes. Then add the garlic and ginger and cook for 1-2 minutes until the everything smells fragrant.
Add the crispy tofu pieces to the onion and pepper mixture and pour over the sweet and sour sauce. Warm through for a further couple of minutes so that the sauce evenly coats the vegetables and the cornflour makes the mixture thick and glossy.
Add the peas to the rice for the final few minutes of cooking time, to defrost, or warm them through before serving equally into bowls.
Top the rice with the sticky tofu and vegetables, and finish with thin slices of spring onion and roasted sesame seeds if you like.