1. Melt butter in a large straight-sided skillet over medium-high heat. Add onion; season with salt and pepper and cook, stirring occasionally, until translucent, about 2 minutes. Add flour; cook 30 seconds. Stir in clam broth, 1 cup water, and potatoes. Bring to a boil, then reduce heat and simmer, covered, until potatoes are tender, 10 to 12 minutes. Meanwhile, cut salmon into 2-inch pieces and corn into 1-inch rounds.

2. Add salmon and corn to skillet. Cook, covered, stirring once, until salmon is opaque and corn is crisp-tender, about 3 minutes. Remove from heat. Stir in cream and basil. Serve, sprinkled with basil leaves and pepper.