In this crowd-pleasing dinner, grilled shrimp is served alongside potatoes and corn with melted butter flavored with Old Bay seasoning, crushed garlic, and lemons. It's the ultimate summer main course.
Heat butter with garlic in a small saucepan over medium heat until melted. Simmer 1 minute. Stir in Old Bay and season with salt. Squeeze juice of halved lemon into butter mixture (reserve halves). Remove from heat; cover to keep warm.
Cover potatoes with 2 inches cold water in a large pot; bring to a boil. Add 2 tablespoons salt, reduce heat to a simmer, and cook until potatoes are just tender when pierced with the tip of a sharp knife, about 12 minutes. Add corn and squeezed lemon halves; return to a boil, then drain.
Preheat grill to medium-high. Brush grates with oil. Toss potatoes, corn, shrimp, and sliced lemons with 2 tablespoons butter mixture in a large bowl. Grill, turning occasionally, until shrimp are cooked through and potatoes, lemons, and corn are marked in spots, about 3 minutes for shrimp, 4 to 5 minutes for vegetables and lemons. Transfer to a large bowl; toss with 1/2 cup butter mixture. Serve with remaining butter mixture on the side.