Dice paneer in cubes. Pat dry them with a clean kitchen towel.
Add them the paneer cubes to a mixing bowl together with red chili powder, black pepper powder, salt and cornstarch.
Gently shake, toss and mix. Everything should be well mixed. You could also mix the corn starch and the spice powders first and then add the paneer cubes to it.
Heat 3 tablespoons oil in a pan or kadai or wok. The oil should be medium hot.
Add the paneer cubes. Flip and pan fry so that all the sides get cooked evenly. For a crisp version, you will need to shallow fry or deep fry the paneer cubes.
Pan fry till the paneer cubes are light golden. Don't fry for a longer period of time as the paneer cubes might become dense.
Place the pan fried paneer cubes on kitchen paper towels.
In the same pan in which the paneer cubes were pan fried there will be some oil. So need to add any oil.
Add the chopped onions, capsicum, ginger, green chilies, garlic and celery. Mix well and stir fry the veggies until the capsicum is half-cooked.
Whilst the veggies are getting stir fried, in the same bowl in which the paneer cubes were mixed, there will be leftover corn starch & the spice powder mixture.
You will only get this dry mixture if the paneer cubes were dry. Add ¼ cup water and make a paste of the remaining corn starch & spice powder mixture.
If the paneer cubes were moist, then you will need to make a separate cornstarch paste. Dissolve 1 tablespoon corn starch with 3 tablespoon water.
Add soy sauce and tomato ketchup to the stir-fried veggies. Adding 1.5 tbsp tomato ketchup make the dish sweet. For an extra sweetness, 2 tbsp tomato ketchup can be added. Stir. You can also add about ½ teaspoon of sugar.
Then season with salt, red chili powder and black pepper. Add less salt as both soy sauce, tomato sauce and the cornstarch paste we made, already has salt in them.
Add the cornstarch paste. Stir well and allow to simmer on a medium heat till the sauce thickens – about 1 to 2 minutes.
Once the manchurian sauce has thickened, then add the pan-fried paneer cubes.
Stir again very well so that the sauce coats the paneer cubes evenly and switch off heat.
Lastly add rice vinegar or apple cider vinegar or regular white vinegar. Stir. Check the taste and add more salt, soy sauce, vinegar or black pepper if required.
Serve dry paneer manchurian snack hot garnished with celery or some spring onion greens. You can also garnish it with chopped coriander leaves or parsley.