Wash tofu nicely under cold water n keep it in warm water for 10 minutes.
After 10 minutes again wash and squeeze gently to take out excess water from it ,cut tofu bar into cubes;k
Now heat 1 tablespoon oil in a nonstick pan n shallow fry the cubes till all sides light golden brown ,remove the tofu in to a plate and keep it aside..
Add all the sauce in a bowl, mix nicely and keep it aside. Heat oil in the same pan add garlic,chillies and onion let it saute for a min or two.
Add bell pepper and saute for a minutes.
Then add all sauce ,salt ,sugar n mix nicely ,stir for a minutes.