Use an 8 or 10-inch (20 or 25 cm) square ceramic or glass dish with a good cover.
Choose a rack on which at least 2 pieces of fish can be placed, although 1 to 6 individual pieces can be steamed at one time.
Pour 1 1/2 to 2 inches (4 to 5 cm) of hot water in bottom of dish â€” or just what is needed to come to the level of the rack.
Place the pieces of fish on a plate or small platter, dot each piece with butter Add a few drops of fresh lemon or lime juice.
Set the plate on the rack.
Cover the dish.
Steam at HIGH 3 minutes per fillet or steak.
Add 1 minute for each additional piece of fish.
When cooked, remove from oven.
Leave cover on, let stand 10 minutes, then serve.