How to Cook Fresh Tuna in the Oven

Although tuna is most commonly sold in cans, many grocery stores and fish markets sell fresh or frozen tuna steaks. Most steaks come already deboned and skinned and cook up quickly — so the following easy tuna steak recipe only takes a few minutes.

For the best baked tuna steak, start with the highest-quality fresh tuna you can get. As the Food and Drug Administration explains, tuna is rich in polyunsaturated fats that, when eaten in place of saturated fat, can help reduce your risk of cardiovascular disease. But that oil content means this heart-healthy fish goes bad fairly quickly.

So look for the firm, dense red flesh and "meaty aroma" that signal you're looking at fresh tuna steaks. Stay away from tuna steaks with marked discoloration or a dull gray hue.

Your choice of fish in the grocery store can have a big impact on the vitality of your favorite species. Many tuna species are already overfished, so opt for (relatively) plentiful varieties caught using sustainable methods.

According to the Monterey Bay Aquarium's Seafood Watch, the best types of fresh tuna to purchase are albacore, yellowfin and skipjack, as long as they're caught with trolling lines, hand lines or poles. Try to avoid varieties of tuna that are caught with less-sustainable methods: drifting longlines, deep-set longlines and purse seines.

Seafood Watch also recommends that you stay away from bluefin and longtail tuna varieties, regardless of the methods by which they're caught.

Read more: Fishing for Answers: Wild-Caught or Farm-Raised Fish — Which Is Better?

Tuna's high oil content and rich flavor means you can add plenty of seasoning without overwhelming it. But don't be afraid to start simple: Pat the steaks dry with paper towels, brush them with olive oil or melted butter, and add salt or pepper to taste.

Other flavorings that go well with tuna include garlic, cayenne pepper, lemon juice (mixed in with the oil or butter) and herbs such as rosemary or tarragon.

If you want to get especially creative, try marinating your tuna. Asian-inspired marinades pair well with this fish; try an easy sweet and savory marinade recipe and soak the meat in the refrigerator for anywhere from 30 minutes to four hours before you put it in the oven.

If your tuna steaks are frozen, defrost them in the refrigerator before cooking. Although searing on a grill or pan is typical, you can also broil or bake your tuna steaks.

To broil the tuna, take a tip from FishWatch and heat your oven, place the marinated tuna steaks in the oven on a well-graded broiler pan, baste the tuna and broil the steaks on a high rack, just a few inches from the heat source.

FishWatch advises a cook time of about three minutes and says that the tuna should be pink in the center when you remove it from the heat.

To bake your tuna, preheat the oven to 450 degrees Fahrenheit and lay the raw tuna steaks out on a single layer on a greased baking sheet, or wrap them individually in oiled foil. You can test the steaks for doneness with a fork: Fresh tuna is typically considered "done" when it begins to flake on the outside but remains pink in the center.

Some people like to eat their tuna red in the center — however, the Centers for Disease Control and Prevention (CDC) recognizes raw and undercooked fish as one of the foods more likely to transmit food-borne illnesses. For food safety, the CDC recommends cooking all seafood to 145 F.

Measure the temperature inside your tuna steaks with a meat thermometer and be ready to leave thick steaks in the oven a little longer than their thin compatriots.

Read more: Food Poisoning Culprits: Sprouts and 7 Other Risky Foods

According to the National Resources Defense Council (NRDC), eating contaminated fish is the No. 1 cause of mercury exposure in America, and tuna is the most common source of mercury exposure. The council goes on to note that mercury exposure can damage your kidneys and nervous system and has the potential to interfere with brain development.

According to the NRDC, ahi and bigeye tuna have particularly high levels of mercury and should be avoided by women who are pregnant, nursing or plan to become pregnant within a year. If you're a woman of childbearing age who likes albacore tuna, the NRDC advises that you consume no more than 4 ounces per week. And finally, you shouldn't feed ahi or bigeye tuna to children under 6 years of age.