Thaw fish, if frozen. Rinse fish; pat dry with paper towels. Cut into four serving-size pieces, if necessary. Place fish on the unheated rack of a broiler pan. Sprinkle fish lightly with salt and pepper.
Preheat broiler. In a small bowl stir together butter and sesame seeds. Measure 1 tablespoon of the butter mixture and set aside for the vegetables. Brush fish with half of the remaining butter mixture. Broil 5 to 6 inches from the heat for 4 minutes; turn fish. Brush with remaining half of the butter mixture. Broil 5 to 6 minutes more or until fish begins to flake when tested with a fork.
Meanwhile, in a 12-inch skillet heat the reserved butter mixture over medium-high heat. Add green beans and orange slices. Cook, covered, for 2 minutes. Uncover; add garlic. Cook, uncovered, for 5 to 6 minutes more or until beans are crisp-tender, stirring frequently. Serve bean mixture with fish.