Seared Tuna Steak with Arugula

This seared tuna steak is coated in sesame seeds, seared quickly in a hot pan so the outside is golden, then sliced and served on peppery arugula with a lemon and olive oil dressing. It takes about 15 minutes and serves 2, with almost 39 g of protein and only about 2 g of net carbs per serving. Traditionally the center is left pink, but you can cook it through, and anyone pregnant or at higher risk of food poisoning should.

• Serves: 2
• Prep time: 10 minutes
• Cook time: 2 to 8 minutes, depending on how you like it
• Total time: about 15 minutes

Ingredients

• 2 tuna steaks, about 150 g (5 oz) each and 2.5 cm (1 inch) thick
• 2 teaspoons reduced-salt soy sauce or tamari
• 1 tablespoon sesame seeds
• 2 teaspoons olive or avocado oil for searing
• 60 g (2 large handfuls) arugula (rocket)
• 2 teaspoons lemon juice, plus wedges to serve
• 2 teaspoons extra virgin olive oil for the dressing
• A pinch of salt and black pepper

Method

1. Take the tuna out of the fridge 10 minutes before cooking. Pat it dry with paper towels.
2. Brush both sides with soy sauce, then press the sesame seeds onto all sides.
3. Heat the oil in a heavy frying pan over high heat until it shimmers.
4. Sear the tuna for about 1 minute per side for a rare center, 2 minutes per side for medium-rare, or 3 to 4 minutes per side to cook it through. Sear the edges briefly too, if you like.
5. Move the tuna to a board and rest it for 2 minutes.
6. Toss the arugula with the lemon juice, olive oil, salt and pepper.
7. Slice the tuna thickly against the grain with a sharp knife and arrange it on the arugula. Serve with lemon wedges.

Is rare tuna safe?

Eating tuna rare or raw is common, but undercooked fish carries a small risk of food poisoning and parasites. The FDA advises cooking most seafood to an internal temperature of 63°C (145°F), when fish flesh is opaque and separates easily with a fork.

If you choose to eat it rare:

• Buy very fresh tuna from a trusted fishmonger and tell them you plan to eat it rare.
• Keep it cold and cook it the day you buy it.
• Use clean boards and knives, and keep raw fish away from other food.

Cook tuna through if you’re pregnant, older, have a weakened immune system, or are cooking for young children. The NHS advises avoiding raw fish in pregnancy. Our guide to foods to avoid during pregnancy has more detail.

Mercury and tuna

Tuna is a larger fish and contains more mercury than salmon, sardines or shrimp. The FDA’s fish advice places yellowfin and albacore tuna in its “good choices” group, which it suggests eating about once a week, while canned light tuna is a “best choice.” Bigeye tuna is on its list of choices to avoid. For people who are pregnant or breastfeeding, and for children, following this advice is especially important.

Tips for perfect seared tuna

• Use a very hot pan. You want a crust in a minute or two without overcooking the inside.
• Choose thick steaks. Thin steaks cook through before they brown.
• Don’t move the tuna while it sears, or the crust won’t form.
• Slice against the grain for tender slices.
• Skip heavy marinades with sugar, which burn quickly.

Swaps and variations

• Peppercorn crust: coat in crushed black pepper instead of sesame.
• Japanese style: serve with a dipping sauce of soy, lime and grated ginger.
• Salad Niçoise: serve on green beans, boiled eggs, olives and tomatoes.
• Salmon: the same method works with thick salmon fillets, cooked through.

Nutrition per serving (estimate)

One serving is one tuna steak with half the salad. These figures were calculated from USDA FoodData Central values for raw yellowfin tuna, olive oil, reduced-salt soy sauce, sesame seeds, arugula, lemon juice and salt.

Yellowfin tuna is very lean and high in protein, which makes this a light, filling meal. Most of the fat comes from the olive oil and sesame seeds. Tuna is lower in omega-3 than salmon or mackerel; our guide to omega-3 foods compares them. The dish is naturally low in carbs, so it suits keto. Our article on whether seafood is keto has more ideas.

Contains: fish, soy, sesame, and wheat (gluten) in soy sauce unless you use tamari.

Storage

Seared tuna is best eaten straight away. If you have leftovers, refrigerate them within 2 hours and eat them within a day, cold in a salad, rather than reheating, which overcooks the fish.

Common questions

What does “sushi-grade” tuna mean?

It’s a marketing term rather than an official standard in most countries. It usually means the fishmonger considers the fish fresh enough to eat raw. Ask how it has been handled and stored.

Can I use frozen tuna steaks?

Yes. Thaw them overnight in the fridge, then pat them very dry before searing.

Safety note: Keto isn’t suitable for everyone. If you have diabetes, kidney or liver disease, take regular medication, or are pregnant or breastfeeding, talk to your doctor before cutting carbs this far (why it matters).

This article is general information, not medical advice. Nutrition figures are estimates from USDA FoodData Central and will change with the brands and amounts you use. If you follow a diet for a medical reason, check the recipe with your doctor or dietitian.