Instructions:
- Preheat grill to medium-high heat (about 375°F/190°C). Tear four large sheets of heavy-duty foil (approx. 18x18) and set aside.
- In a small bowl, whisk together the melted butter, Old Bay, smoked paprika, garlic powder, cayenne, lemon zest, and black pepper to create the seasoning butter.
- In a large mixing bowl, combine the prepared shrimp, sausage, potatoes, corn, and onion wedges.
- Pour about 3/4 of the seasoned butter mixture over the contents of the large bowl. Toss thoroughly until everything is evenly coated. Reserve the remaining butter.
- Divide the coated mixture evenly onto the centre of each foil sheet. Top each pile with 2-3 thin lemon slices.
- Assemble the packets by bringing the long edges of the foil together over the food. Fold the edges over several times to create a tight seal, then fold up the short ends securely. Ensure there is some headspace for steam.
- Place the sealed packets directly onto the preheated grill grates. Cook for 12–15 minutes.
- Carefully open one packet (watch for steam). Check for doneness: shrimp should be pink and potatoes easily pierced. If needed, return to the grill for 2-3 more minutes.
- Transfer the packets to plates. Open them fully at the table for the steam release. Drizzle with any reserved melted butter and garnish generously with fresh chopped parsley before serving.