In a large bowl, mix 200 grams of thick curd, 1 tablespoon ginger-garlic paste, 1 teaspoon red chilli powder, 1/2 teaspoon turmeric powder, 1 teaspoon garam masala, 1 tablespoon lemon juice, salt to taste, and 2 tablespoons mustard oil to create the marinade.
Cut 500 grams of boneless chicken into 2-inch cubes and add them to the marinade. Mix well ensuring each piece is coated. Cover and refrigerate for at least 2 hours, or overnight for best results.
Preheat your grill to a medium-high heat (about 200°C).
Thread the marinated chicken pieces onto skewers, leaving a small space between each piece.
Place the skewers on the grill and cook for about 12-15 minutes, turning occasionally, until the chicken is thoroughly cooked and has a nice char on the outside.
Brush the kababs with a little melted butter or oil during the last few minutes of grilling for an extra rich flavor.
Serve hot, garnished with slices of onion, lemon wedges, and fresh coriander leaves.