Cut the paneer into 1/2- by 1 1/2-inch rectangles. You can use this paneer as is in step 5, but if you would like to fry the paneer (as is commonly done), heat 1/4 cup of the oil/ghee in a large skillet over medium-high heat. As soon as the oil is hot, reduce the heat to medium-low and then fry the paneer pieces in batches until golden brown on each side (30 to 40 seconds per side). Transfer the fried paneer onto a dish lined with absorbent kitchen paper towels to drain the excess fat. Keep aside until ready to use.
Heat the 2 tablespoons of oil/ghee in a large deep and thick bottomed saucepan on medium-high heat. Once the oil is hot, add the onions and fry them until light brown, 5 to 6 minutes.
Add the ginger and garlic to the onions and cook, stirring, for another 30 seconds. Then add the coriander, turmeric, chili, pepper, and garam masala. Stir and cook for 30 seconds.
Add the crushed tomatoes along with the juice and stir and cook until the sauce starts to thicken, 10 to 12 minutes.
Reduce the heat to medium-low. Add the paneer, peas, and salt and fold into the tomato sauce, taking care to avoid breaking the paneer. Add 3/4 cup of room temperature tap water and cover the saucepan with a lid. Cook for about 8 to 12 minutes, until the peas are tender (frozen peas will cook faster than fresh peas, so watch and taste the peas after 8 minutes to see if they are soft but not mushy). Taste the sauce and adjust seasoning if necessary.
Garnish with fresh cilantro leaves and serve hot with warm naan or plain rice.
Nik Sharma is the writer, photographer, and recipe developer behind A Brown Table, an award-winning blog that has garnered best-ofs from Saveur, Better Homes & Gardens, and the International Association of Culinary Professions. His weekly column, A Brown Kitchen, appears in the San Francisco Chronicle and has written for Saveur, Taste, Food52, Eater, among others. His first cookbook, Season: Big Flavors, Beautiful Food was released on October 2018. He was also featured in America, the Great Cookbook. Nik lives in Oakland, California.