If using store-bought paneer, soak it in hot water for 10 minutes and drain. Arrange one oven rack in the center of the oven and a second one closest to the broiler heating element. Heat oven to 450 degrees. Line a large sheet pan with foil and brush it with 1 tablespoon oil. Set aside.
In a large bowl, mix the rest of the oil with yogurt, ginger paste, garlic paste, coriander powder, garam masala, red chile powder, turmeric powder and 1 teaspoon salt to make the marinade.
Add paneer, bell peppers and onion to the bowl with the marinade and mix until evenly coated. (If you have the time, marinate the paneer and vegetables for 20 minutes and up to 2 hours for even more flavor.)
On the prepared sheet pan, evenly spread out the marinated paneer and vegetables, and bake on the middle oven rack until the paneer edges start to turn golden, about 8 minutes.
Take the pan out of the oven and brush the paneer with melted ghee. Turn the oven to broil, place the paneer and vegetables on the top rack and broil on high until the paneer turns golden, 1 to 2 minutes. Take the paneer and vegetables out of the oven and sprinkle with lemon juice and additional salt, if desired. Serve with roti and chutney or by itself.