In a large bowl, combine flour, 2 tablespoons of the cornstarch, garlic, pepper, salt and 6 tablespoons water to make a thick paste.
Place paneer in the paste and let it marinate for 10 minutes. Heat enough oil for deep frying in a wok or skillet. Remove the paneer pieces from the marinade. Place in the hot oil and fry until golden brown. Remove to a paper towel lined plate.
Remove all but 2 tablespoons of oil in the skillet. Add ginger and garlic paste and fry for 1 minute.
Add onion and fry until golden. Add soy sauce, sugar, tomato sauce and chilli sauce.
Add bell peppers and chillies. Fry for 5 minutes, until the peppers start to char.
Add paneer pieces and cook for another 2 minutes.
In a small bowl, dissolve the remaining cornstarch in 3 tablespoons of water. Add this to skillet and cook for another 2 minutes.