Start by marinating 500 grams of chicken or paneer in a mixture of 2 tablespoons of olive oil, 1 tablespoon of lemon juice, 1 teaspoon of cumin powder, 1 teaspoon of red chilli powder, salt to taste, and 1 teaspoon of black pepper powder. Let it sit for at least 30 minutes.
Heat 2 tablespoons of oil in a pan over medium heat. Add 1 large sliced onion and 2 sliced bell peppers (one red and one green for colour). Sauté until they are soft and slightly caramelized. Remove them from the pan and set aside.
In the same pan, add the marinated chicken or paneer and cook until it is fully cooked and slightly charred on the edges.
Return the sautéed onions and bell peppers to the pan and mix well. Cook for another 2-3 minutes.
Serve the fajitas with warm tortillas, salsa, and sour cream.