In the same pan, there will be some oil left. So no need to add any extra oil. Add 2 teaspoons finely chopped ginger, 2 teaspoons finely chopped garlic and 2 to 3 green chillies (slit or sliced).
Stir fry on medium to high flame for some seconds.
Then add ⅓ cup chopped spring onions.
Stir fry spring onions for 1 to 2 minutes on medium to high flame.
Next add ½ cup sliced capsicum.
Stir fry on medium to high flame for 3 to 4 minutes. The capsicum only needs to be slightly cooked.
Lower the flame and then add ½ teaspoon kashmiri red chilli powder.
Then add 2 teaspoons soy sauce and 1 teaspoon red chilli sauce.
Stir and mix the sauces and red chilli powder with the remaining stir fried ingredients.
Add ½ to ⅔ cup water. mix well.
Let the mixture come to a simmer on medium to medium-high flame.
Meanwhile take 1 tablespoon cornstarch in a small bowl.
Add 2 to 3 tablespoons water for dissolving corn starch. Corn starch is known as corn flour in india.
Mix very well to get a smooth paste.
Lower the flame and then add this corn starch paste to the gravy.
As soon as you add corn flour paste to the gravy, mix the paste very well so that no lumps are formed.
Add ½ to 1 teaspoon sugar or as required.
Season with salt as per taste. Do keep a check on salt as soy sauce and red chilli sauce already have salt in them.
Mix very well and simmer till the sauce has slightly thickened and the corn starch has cooked. You can check the taste and you should not feel any raw taste coming from the corn starch in the sauce.
Add the fried paneer cubes.
Mix paneer cubes very well with the gravy.
Switch off the flame and then add ¼ to ½ teaspoon rice vinegar or white vinegar. You can skip vinegar if you want.
Then add about 2 to 3 tablespoons of chopped spring onions greens.
Mix very well. Check the taste of gravy and if you want, you can add more soy sauce, chilli sauce, salt, black pepper or sugar.
Serve restaurant-style chilli paneer garnished with some spring onions.