Place potatoes in a medium saucepan and cover with cold water by 1 inch. Add 1/2 tsp salt, bring to a boil, then reduce to a simmer and cook until just tender, 10–12 minutes. Drain and set aside.

Cook corn

If using fresh corn, bring a second pot of water to a boil, add corn pieces and cook 4–6 minutes until tender. Drain and set aside. If using frozen corn, blanch 1–2 minutes or thaw and drain.

Cook Sausage

Sear sausage

In a large, heavy skillet or Dutch oven over medium-high heat, add 1 tbsp olive oil. Add sliced sausage and cook 3–4 minutes per side, stirring occasionally, until browned and slightly crisp. Transfer sausage to a plate and reserve drippings in the pan.

Make Butter Sauce & Finish Seafood

Sauté aromatics

Lower heat to medium. Add remaining 1 tbsp olive oil to the pan with reserved drippings if needed. Add finely chopped shallots and sauté 2–3 minutes until softened. Add minced garlic and cook 30–45 seconds until fragrant, stirring constantly to avoid burning.

Deglaze

Pour in white wine (or chicken broth) and use a wooden spoon to scrape any browned bits from the bottom of the pan. Let the liquid reduce by about half, 1–2 minutes.

Add butter and seasonings

Reduce heat to low and add the unsalted butter in several pieces, stirring until melted and smooth. Stir in lemon juice, Old Bay seasoning, smoked paprika, crushed red pepper flakes (if using), salt, and black pepper. Taste and adjust seasoning.

Combine vegetables and sausage

Return the cooked potatoes, corn pieces, and browned sausage to the pan and toss gently in the butter sauce to coat and warm through, about 2 minutes.

Cook shrimp & crawfish

Push the vegetables and sausage to the sides of the pan to create space in the center. Add shrimp in a single layer and cook 1–2 minutes per side until pink and just opaque. Add crawfish tails and cooked crab meat, gently folding them into the butter sauce; cook 1–2 more minutes just to heat through (do not overcook). If sauce looks too thick, add up to 2 tbsp reserved cooking liquid or broth to loosen.

Finish

Stir in chopped parsley and chives, then remove the pan from heat. Squeeze a little additional lemon juice over the top if desired. Taste and adjust salt/pepper.

Serve

Transfer the butter seafood medley to a large serving platter or serve family-style from the pan. Garnish with extra chopped parsley, green onions, and lemon wedges. Serve immediately with crusty bread to soak up the sauce or steamed rice.