Cooking the fillets in foil pretty much steams them and it is so very easy to do. This is a nice mild way to serve fish and I think the preparation would do just as well on meaty fish steaks such as tuna or swordfish.

4 servings
143 calories per serving

4 4 oz. cod, tilapia or flounder fillets
¼ t pepper
1 ½ t oil
1 ½ t dried onion flakes
1 clove garlic, minced
¾ t ground cumin
2 T minced cilantro
1 lime peeled and thinly sliced
1 T margarine, melted

Preheat the oven to 375 degrees. Place each fish fillet on a piece of aluminum foil and sprinkle with pepper. Heat oil and add onion flakes and garlic and cook 1 minute them add cumin and place the mix over the fish. Sprinkle fish with cilantro and add a few lime slices to each fillet. Fold the foil over securely so the fish can steam and place the packets on a baking dish and bake 35-40 minutes.

For instructions on folding, Reynold’s says:
For each foil packet, bring up the two sides of the foil and double fold with about 1-inch wide folds. Leave room for heat circulation inside the packet as the food cooks. Double fold each end to form the foil packet.

And the Scouts site has a nice diagram.