Dice paneer into equal size pieces. In a separate bowl mix cornflour with chopped ginger garlic and salt and pepper as required. Add paneer pieces into the mix and stir such that the paneer gets coated with the dry mic properly. Refrigerate it for 5-7 mins.
Heat 2-3 tbsp oil in a wok and fry the marinated paneer pieces till light golden in color. Do not over fry it as it may get dense.
Drain the paneer cubes into a kitchen napkin and keep aside.
Remove extra oil from the wok such that only 1 tbsp oil is left for making the manchurian.
Now in the left oil, add chopped ginger and garlic and saute. Now add onion and bell peppers along with some chopped green chilies and saute all together for few minutes.
Now add soy sauce, tomato sauce and vegetable stock. Cook for another few minutes till the mixture begins to reduce.
Now add the cornflour paste and keep stirring to avoid forming lumps.
Simmer the gas flames and keep stirring till the sauce begins to thicken.
Once you get the desired consistency of the sauce add fried paneer cubes, pepper powder, sugar, vinegar and salt as needed.
Stir and cook for another 1-2 minutes and turn off the gas.
Serve hot with stir fry noodles or plain/fried rice !