Combine melted butter and garlic; reserve.
Peel the onion and cut from top to bottom. Place cut side down and cut each half into six wedges (widest part of the onion should be 1/2"). Break wedges apart so two or three layers of onion stay together. Steam the onions approximately 3 minutes to soften slightly.
Remove the core from the tomato. Slice the tomato in half from top to bottom. Place cut side down and cut each half into three wedges. Remove the pulp and seeds from each wedge.
Cut zucchini into 1/2 slices. Cut small slices (1 1/2-inch diameter or less) into two pieces; cut large slices (over 1 1/2-inch diameter) into three pieces lengthwise (do not cut into wedges).
Thread items onto skewer in this order, three shrimp (about 1/2 from the thick end), onion wedge, zucchini, tomato, three shrimp, onion wedge, zucchini, tomato, three shrimp.
Brush skewers with butter mixture. Sprinkle with salt and pepper. Refrigerate until ready to cook.
Lightly brush charcoal grill rack with oil, place skewer on grill rack and cook over medium coals until shrimp are done and vegetables cooked, about 8 - 10 minutes. Turn once or twice while cooking to prevent burning. Or place on broiler pan. Broil about 4 inches from source of heat for 8 minutes, turning once while cooking.
Chef's Tip: Optional Harpoon (Kabob) ingredients: mushroom caps, cherry tomatoes, yellow squash pieces, pineapple chunks, olives, or use your imagination.Makes 4 Source: