Slow-Cooker Shrimp & Crab Bisque

Name: Slow-Cooker Shrimp & Crab Bisque
Prep time: 10 min
Cook time: 2 h 30 min
Total time: 2 h 40 min
Cuisine: Southern, American
Ingredients: 1 tablespoon olive oil; 2 tablespoons butter; 2 leeks, white and light green parts only, washed well and chopped; 4 garlic cloves, minced; ½ teaspoon red pepper flakes (can add more, to taste); 2 tablespoons tomato paste; 1 cup dry sherry or marsala wine; 4 cups seafood or fish stock; 1 (15-oz) can diced tomatoes; 1 teaspoon Old Bay seasoning; 1 tablespoon sugar; 1 cup water; ¼ cup all-purpose flour; 2 teaspoons kosher salt; 1 teaspoon black pepper; 1 cup half-and-half or heavy cream; 1 lb peeled and deveined shrimp; 1 cup jumbo lump crab meat; Fresh parsley and lemon wedges, for serving; Toasted bread or croutons, for serving; Juice of ½ a lemon; 2 tablespoons mayo; 1 teaspoon Dijon mustard; 1 teaspoon whole grain mustard; 1 tablespoon chopped fresh parsley; Salt, to taste