1 teaspoon olive oil
1 onion, minced
1/3 cup all-purpose flour
1 quart half-and-half, or as needed
2 cups bar clams, drained with juice reserved
1/3 cup grated Parmigiano-Reggiano cheese
2 potatoes, cubed
2 cups cream-style corn
1 large ear corn, kernels cut from the cob
1 cup sliced cherry tomatoes
1 1/2 cups water, or as needed
sea salt and coarsely ground black pepper to taste
1 fresh haddock fillet, cut into 1-inch pieces
2 cups large shrimp, peeled and deveined
1 cup canned lobster meat, with juice
Melt butter with olive oil in a large pot over medium-low heat; stir in onion and sauté until translucent, about 5 minutes. Whisk flour into butter mixture; whisk in half-and-half and juice from drained clams. Stir Parmigiano-Reggiano cheese into onion mixture until melted, about 2 minutes; stir in potatoes, cream-style corn, corn kernels, and cherry tomatoes. If soup is very thick, stir in water, about 1/2 cup at a time, as desired; bring soup to a simmer and cook until potatoes are tender, about 15 minutes. Season with sea salt and pepper. Stir drained clams, haddock, and shrimp into soup; simmer until haddock and shrimp are fully cooked for 5 minutes. Stir in lobster and its juice; cook just until heated through.