Leftover Grilled Salmon Chowder

Name: Leftover Grilled Salmon Chowder
Ingredients: 5 small red potatoes, cut into bite-size pieces; 2 tablespoons olive oil; 1 onion, diced; 2 stalks celery, thinly sliced; 2 tablespoons all-purpose flour, or as needed; 1/2 teaspoon salt; 1/4 teaspoon ground black pepper; 4 cups 2% milk; 1 cooked salmon fillet, flaked; 1 1/4 cups frozen peas; 1 1/4 cups frozen corn; 1 teaspoon dried dill weed; 1/2 cup shredded reduced-fat Swiss cheese; 1/2 cup shredded reduced-fat Cheddar cheese; 1 green onion, finely chopped