low country boil recipe

**Ingredients**: - 4 quarts (3.8 liters) water - 1/4 cup (60 g) Old Bay seasoning - 1 tablespoon salt - 2 pounds (900 g) small red potatoes - 1 large onion, quartered - 1 lemon, halved - 3 cloves garlic, smashed - 2 pounds (900 g) smoked sausage, cut into 1-inch pieces - 4 ears of corn, cut into thirds - 2 pounds (900 g) large shrimp, deveined (leave shells on) - Optional: 1 pound (450 g) crab legs or crawfish - 1/4 cup (60 g) butter, melted - Fresh parsley, chopped (for garnish) - Lemon wedges (for serving)