Rinse shrimp and pat dry; leave shells on for flavor but remove vein if not already deveined. If shrimp are frozen, thaw completely. Halve large potatoes; cut corn into 3–4 pieces each; halve smoked sausage lengthwise and then into 1–2 inch pieces; quarter the onion; smash or coarsely chop the garlic; cut lemon into wedges.

Make the boil

Bring seasoned water to a boil

In a large stockpot (6–8 quart), combine 2 quarts water, kosher salt (1 tablespoon), 3 tablespoons Old Bay seasoning, bay leaves, crushed garlic cloves, and black pepper. Bring to a rolling boil over high heat.

Cook potatoes

Add the potatoes to the boiling, seasoned water. Reduce heat to maintain a steady boil and cook uncovered for 10 minutes, or until potatoes are just tender when pierced with a fork.

Add sausage and corn

Add the smoked sausage pieces and corn segments to the pot. Continue boiling for 5–7 minutes, until the corn is nearly tender.

Add onion

Tuck the quartered onion into the pot and boil for an additional 2 minutes to soften and flavor the broth.

Finish with shrimp

Add the jumbo shrimp to the pot and cook for 2–3 minutes, or until shrimp are opaque, pink, and just cooked through. Do not overcook.

Optional spice boost

If you want more heat, sprinkle crushed red pepper flakes into the pot during the last minute of cooking.

Drain, toss & serve

Drain and arrange

Carefully drain the contents of the pot in a large colander or use a slotted spoon to transfer shrimp, sausage, corn, potatoes and onion to a large serving tray or parchment-lined table (classic peel-and-eat presentation). Discard bay leaves and garlic pieces.

Butter toss

Drizzle the melted butter over the hot seafood and vegetables (reserve 1 tablespoon butter for passing, if desired). Toss gently so the butter and remaining seasoning coat everything evenly. Taste and sprinkle additional Old Bay or kosher salt if needed.

Garnish & serve

Sprinkle chopped parsley over the platter and serve immediately with lemon wedges for squeezing. Provide small forks or seafood picks, butter for dipping, and napkins for a casual peel-and-eat meal.