1. Mash butter, scallion, lime zest and juice, 1/4 teaspoon salt, and red pepper flakes in a small bowl until combined. Transfer to the center of a piece of plastic and wrap to form a 3"-long log; twist ends of plastic to tighten. Chill until firm, at least 1 hour.
2. When ready to cook, remove fish from fridge and let sit 10 minutes. Meanwhile, place zucchini rounds in a colander set over a large bowl. Toss with 1/2 teaspoon salt and drain for 10 minutes, then pat dry (do not rinse). Heat primary grill burner to high and other burners to low, then clean and oil grates.
3. Cut four 16"-long pieces of foil and place on counter. Divide zucchini and tomatoes evenly among foil sheets, placing vegetables on one side of each piece; top with a thin slice of prepared butter. Place one fish fillet on top of vegetables and season with salt and pepper. Fold foil over fish and vegetables and crimp edges together to form a tightly sealed packet. Repeat with remaining fillets.
4. Prepare for indirect grilling by leaving primary burner on high and turning off burners set to low. Place packets away from heat source, close lid, and grill until fish flakes easily and is opaque throughout, 10 to 15 minutes, rotating packet positions midway through cooking (do not flip). Remove packets from grill and set aside (keep packets closed). Heat all burners to high and grill bread until well marked, about 1 minute per side.
5. Carefully open packets, avoiding hot steam, and transfer fish and vegetables to four plates. Top each fillet with a 1/4"-thick slice of prepared butter. Serve with grilled bread.
Source: Hannaford fresh Magazine, July - August 2019