Fry 200 grams of small paneer cubes in 1 tsp of ghee (clarified butter) and keep them aside when done. (Pro tip: Frying the paneer pieces in ghee adds to the flavor. If you prefer, you can fry them in cooking oil as well.)
In the remaining ghee, fry 1 piece of ginger (2-inch size, diced into small pieces) and 12 cloves of garlic (peeled, whole) first and then add ½ cup of onion (large size, finely sliced) and ½ cup of tomato (large size, roughly chopped) to it. Fry them until soft. (Pro tip: You may add a few pieces of cashew nuts while frying the onions and tomatoes and blend it. This will make your kadai paneer richer and taste more delicious.)
Remove them to a blending jar and make a fine paste.
Fry ½ cup of onion and ½ cup of capsicum, both medium size and cut into diamond shape in 2 tbsp of cooking oil in the kadai. Remove them when done.
Now, heat 3 tbsp of cooking oil in the kadai again. Fry the onion and tomato paste for about a minute or two.
Add 1 tbsp of sabzi masala powder. Mix nicely and cover the kadai to cook it for about 3 to 4 minutes on a low flame. (Pro tip: If you do not have sabzi masala powder at home, you can use a mixture of ½ tsp of cumin powder, 1 tsp of coriander powder, 1/3 tsp of turmeric powder, 1 tsp of red chili powder, and ½ tsp of garam masala powder.)
Switch off the stove and let the masala cool down a bit before adding 1 tbsp of Dahi to it. Mix it nicely. Now, turn on the gas stove, cover the masala and cook it for 3 to 4 minutes more on a medium flame.
Add 1.5 cups of water to the masala and mix nicely. Cover the kadai and cook until the water comes to a boil.
Add the fried paneer cubes, capsicum and onion to it. Also, add salt to taste and mix everything very nicely. Cover the kadai and let it cook for about 2 minutes on a medium flame.
Finally, add a handful of finely chopped coriander leaves and 1 tsp of ghee to it and mix nicely. Cover the kadai and let it cook for another 30 seconds.
Check its doneness. Transfer it to a serving tray.
Your tasty and creamy homemade kadai paneer is ready to enjoy with plain roti, tandoori roti, naan or kulcha.