Prep the paneer and veggies: Cut paneer into 1-inch cubes. Slice bell peppers and onion into bite-sized pieces.
Pat paneer dry with a paper towel so the marinade sticks well.
Make the marinade: In a bowl, whisk together yogurt, lemon juice, ginger-garlic paste, Kashmiri chili powder, red chili powder, turmeric, garam masala, cumin, coriander, ajwain, kasuri methi, salt, and oil until smooth.
Marinate: Gently fold in paneer, peppers, and onions. Coat everything evenly without breaking the paneer. Cover and let it sit for 20–30 minutes at room temperature, or up to 2 hours in the fridge.
Skewer (optional): If grilling or baking, thread paneer, peppers, and onions onto skewers.
If using wooden skewers, soak them in water for 20 minutes first.
Choose your cooking method: Oven: Preheat to 425°F (220°C). Place skewers or pieces on a lined baking sheet with a rack. Brush lightly with oil.
Bake 12–15 minutes, turning once. Broil 1–2 minutes to char.
Stovetop: Heat a heavy skillet or grill pan over medium-high. Add a thin layer of oil.
Cook paneer and veggies 6–8 minutes, turning to brown all sides.
Outdoor grill: Preheat to medium-high. Oil the grates well. Grill skewers 6–8 minutes, turning until lightly charred.
Finish and serve: Sprinkle with chopped cilantro.
Squeeze fresh lemon on top. Serve hot with mint-cilantro yogurt chutney.