Pull beards (if any) off mussels and place in a bowl filled with well-salted cold water; do the same with clams. Allow to sit for 45 minutes to an hour; drain and rinse shellfish. Cut fish into 2-inch pieces. Slice squid bodies crosswise and separate tentacle clumps if large.

Peel potatoes and dice into ½-inch pieces. Cut celery into ½-inch pieces. Chop onion and garlic. Chop whole tomatoes or blend briefly.

Sauté onion, celery and garlic in olive oil in a large, broad saucepan, stirring until translucent but not browned. Stir in tomato paste until incorporated.

Add potatoes, tomatoes, seafood broth, wine and bay leaves. Bring to a simmer and cook about 15 minutes. Taste and add salt if needed. Add paprika, starting with the smaller amount; taste before adding more.

Add fish and squid. Bring to a simmer and cook, partially covered, about 10 minutes or until cooked through. Add shrimp and beans, cooking until shrimp turns opaque.

Cover the bottom of a large skillet or deep saucepan with some sauce. Add mussels and clams. Cook over medium-high heat until shellfish open (mussels will open first), about 8 minutes. Tilt the skillet to pour cooking juices into stew. Add more broth if needed and taste, adding more salt and paprika if needed.

Spoon the stew into large, shallow bowls. Garnish with equal quantities of mussels and clams. Sprinkle with parsley.