Heat oil in a deep frying pan. Shallow fry the marinated paneer cubes until light golden in color and crisp from both sides. Do not turn the paneer cubes again and again while frying. Transfer to a plate and set aside.
In the same pan add ginger and garlic. Stir fry for a minute. Add onion, and stir-fry over a high flame for 1 - 2 minutes or till onion soften a bit.
Add the capsicum and sauté for a minute or so.
Next add vinegar, soy sauce, chili sauce, salt, and mix nicely.
Now, add the cornflour paste and stir the sauce continuously to avoid any lump formation.
The sauce will start thickening now. Taste and adjust the seasoning accordingly
Once the sauce thickens, add fried paneer cubes. Stir to combine. Allow the sauce to simmer over low heat for 5 - 6 minutes for paneer to absorb the flavor.
Garnish the chilli paneer with chopped spring onion greens.
Serve Chilli Paneer with fried rice.