Although tuna won't have a crispy char on the outside when you cook it gently in the microwave, it can still be tender and succulent if you cook it with care. Choose fresh tuna over frozen for the best flavor and quality. Because tuna contains mercury, a metal hazardous to your health, the U.S. Food and Drug Administration recommends that adults eat no more than 6 ounces per week and that children and pregnant women eat 1 to 3 ounces per week.
Choosing Tuna to Microwave
As long as you monitor it carefully, any variety of tuna cooks well in the microwave. Although your choices may be limited to the selection at your local, reputable fish market, always choose tuna steaks that look fresh, without any browning or drying and with limited liquid in the packaging. The more oil in tuna and the thicker the cut, the less chance that you'll overcook the fish. Choose oil-rich bluefin and albacore over medium-fat yellowfin.
Preparing the Tuna
Thaw frozen tuna overnight in the refrigerator, and then prepare it the same way you would fresh tuna. Marinate the tuna for about an hour to enhance its flavors. For an Asian-inspired marinade, blend soy sauce, fresh minced ginger, minced garlic, sesame oil and vegetable oil; substitute orange or lemon juice for the sesame oil for a tangy citrus marinade. Cut large pieces of tuna into steaks at least 1-inch thick.
Cooking the Fish
If you've marinated the tuna, use that liquid for cooking the fish; for fish without a marinade, add about 1/4 cup of water in the microwave pan for each pound of fish. Cook the tuna on high power for about 1 1/2 minutes per side for each pound of tuna. For smaller steaks, cook for only 45 seconds per pound before checking for doneness. The tuna is cooked when if flakes easily or has reached 145 degrees Fahrenheit on an instant-read thermometer.
Using Microwaved Tuna
Microwave cooking is similar to poaching, and you can prepare the tuna for serving the same way you would any poached fish. For example, top it with a creamy dill or cucumber sauce made with equal parts mayonnaise and yogurt or sour cream with plenty of fresh, chopped dill and diced cucumber. Microwaved tuna also works well when you break the steaks into large chunks for a salad nicoise, a classic French salad with tuna, green beans, black olives, hard-boiled eggs, onions and herbs.