Coat a Dutch oven with nonstick cooking spray; heat pan. Add onions. Cook and stir, uncovered, over medium-high heat about 7 minutes or until tender. Add red pepper, yellow pepper, green pepper, and banana pepper. Cook and stir for 1 minute more. Carefully add broth. Bring just to boiling; reduce heat. Simmer, uncovered, for 10 minutes. Stir in whipping cream. Return to boiling; reduce heat. Simmer for 10 minutes.
Meanwhile, rub caraway seed and salt on both sides of fish. Coat a medium skillet with nonstick cooking spray; heat skillet. Cook fillets, uncovered, over medium-high heat for 3 to 4 minutes per side or until fish flakes easily with a fork.
To serve, place a salmon fillet in each of four shallow soup bowls. Ladle soup mixture over salmon fillets. Top with dill sprigs. Makes 4 servings.