Grind spinach leaves, coriander leaves, and green chilies into a smooth paste.

In a bowl, combine the spinach-coriander paste with red chili powder, dried mango powder (amchoor powder), garam masala powder, salt, dried fenugreek leaves (kasoori methi), and ajwain.

Add the beaten low-fat plain yogurt to the marinade and mix well.

Gently add the cut and cleaned red snapper pieces to the marinade, ensuring they are fully coated.

Let the fish marinate for at least 25 minutes to allow the flavors to penetrate.

Preheat your barbecue grill to medium heat.

Carefully skewer the marinated fish pieces onto skewers.

Place the skewers on the barbecue grill and cook for 10-12 minutes, turning occasionally.

Baste the fish with a little oil while barbecuing to keep it moist.

Continue to barbecue the fish until it flakes easily with a fork, indicating it is cooked through.

Serve the hot barbecued green fish on a bed of sliced onions.

Garnish with sauteed garlic for added flavor.