1.Finely shred 2 teaspoons peel from the limes; set aside. Thinly slice limes and lay slices evenly in the bottom of a steamer basket. Place the fish in a single layer on top of the lime slices. Stir ginger, reserved lime peel, salt, and pepper into sesame oil; brush generously over fish.
2.Place fresh or frozen beans in the upper section of the steamer container. Steam the fish and beans according to the manufacturers directions for 12 to 15 minutes or until just cooked through. (If beans are not tiny, you may need to remove the fish and steam beans for an additional 4 to 5 minutes.) Let stand 1 minute.
3.To serve, arrange beans in a serving dish; remove fish from lime slices and arrange fish on top of beans. If desired, serve with lime wedges. Makes 3 servings.