How to Make It
Preheat oven to 500°.
Place tomatoes, cut sides up, on a foil-lined baking sheet coated with cooking spray. Coat tomatoes with cooking spray; sprinkle evenly with 1/4 teaspoon salt and 1/4 teaspoon pepper. Bake at 500° for 5 minutes.
Reduce oven temperature to 450° (do not remove pan from oven). Combine 1/4 teaspoon salt, oil, garlic, and green beans on a large piece of foil; toss to coat. Fold foil over, and seal tightly to form a packet. Place packet on baking sheet with tomatoes; bake at 450° for 20 minutes.
Combine mayonnaise, juice, tarragon, and Dijon in a bowl, stirring with a whisk. Sprinkle fillets evenly with remaining 1/4 teaspoon salt and remaining 1/4 teaspoon pepper. Spread mayonnaise mixture evenly over 1 side of fillets. Top evenly with panko, and coat with cooking spray.
Remove pan from oven. Move tomatoes and packet to 1 side of pan. Arrange fillets on other side of pan. Bake at 450° for 6 minutes. Turn broiler to high (do not remove pan from oven). Broil 3 minutes or until panko is golden and fish flakes easily when tested with a fork. Serve with green beans, tomatoes, and lemon.