Step 1

Pound garlic, turmeric, and ½ tsp. salt in a mortar and pestle to a coarse paste (alternatively, pulse in a food processor). Transfer to a large bowl and mix in shallot, scallions, chiles, lemongrass, sugar, lime juice, fish sauce, and 2 Tbsp. water. Season fish with salt and toss to coat in marinade. Let sit at room temperature 1 hour, or cover and chill up to 4 hours.

Step 2

Prepare grill for medium-high heat. Keeping marinade on fish, place each fillet between 2 ti leaves or 2 sheets of foil and grill until cooked through, about 5 minutes per side (thicker fillets will take longer).

Step 3

Transfer fish to a platter lined with more ti leaves, if using. Serve with rice and lime wedges.