1. Melt butter in a large saucepan over medium heat. Add onion and potato, and cook, stirring often, 5 minutes. Add flour, and cook, stirring constantly, 1 minute. Add broth, and bring to a boil; reduce heat, and simmer, covered, 5 minutes or just until potato is tender.
2. Stir in corn and next 4 ingredients; return to a simmer, stirring occasionally. Add salmon, and simmer 4 minutes or just until fish flakes. Add lemon juice and fresh herbs; season with additional sea salt and pepper, if desired.