Take a mixing bowl and add thick yogurt (curd) to it. Use a whisk or spoon to stir the yogurt until smooth and creamy.
Add gram flour (chickpea flour), ginger-garlic paste, turmeric powder, red chili powder (cayenne or paprika), garam masala, cumin powder, chaat masala, lemon juice, mustard oil (or olive oil), and salt. Mix everything well to form a smooth and thick marinade.
Add paneer cubes, bell peppers, and onions to the prepared yogurt marinade and toss gently until everything is evenly coated. Cover and refrigerate for at least 30 minutes, or overnight for deeper flavor.
Preheat your oven to 200°C (390°F) for 10 minutes and line or lightly grease a baking tray to ensure even roasting for this oven-baked paneer tikka.
Thread marinated paneer, bell peppers and onion alternately onto wooden or metal skewers to assemble kebabs, spacing pieces evenly for uniform cooking and attractive presentation.
Bake the skewers at 200°C for 12–15 minutes, turning once halfway for even golden color, then broil/grill 2–3 minutes if you want smoky, charred grill marks and a crisp exterior.
Remove paneer tikka from skewers and plate as a vegetarian appetizer, finishing with a sprinkle of chaat masala, chopped coriander (cilantro), lemon wedges and a side of mint chutney for tangy, refreshing contrast.