Ingreadient

• 3 tablespoons unsalted butter
• 1 small onion, finely chopped
• kosher salt and freshly ground pepper
• 1 tablespoon unbleached all-purpose flour
• 2 jars (each 8 ounces) clam broth
• 12 ounces yukon gold potatoes, scrubbed and cut into ½-inch pieces
• 1 pound skinless salmon fillet
• 2 ears corn, shucked
• ¼ cup heavy cream
• ¼ cup thinly sliced fresh basil
• basil leaves, for serving