- Prep
- 10 min
- Cook
- 6 min
- Total
- 16 min
- Serves
- 2
Ingredients
What you’ll need — tap to tick off as you go
- 2 tbsp
- 1 tsp
- 1 tbsp
- 1 tbsp
- 2 tbsp
- 1 tsp
- 1 clove
- 1 pinch
- 1 pinch
Process
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Pat the tuna steaks completely dry with paper towels, then season both sides with sea salt and black pepper. Dry fish is the difference between a crust and steam.
In a small bowl whisk 2 tbsp soy sauce, the juice of half the lime, 1 tsp honey, 1 tbsp sesame oil, 1 tsp grated ginger and 1 grated garlic clove. Pour half into a shallow dish, add the tuna, and turn to coat. Leave for 5 minutes only.
Spread 2 tbsp sesame seeds on a plate. Press each tuna steak into the seeds on all sides so a thin even layer sticks.
Heat 1 tbsp neutral oil in a heavy skillet over high heat until it shimmers and a sesame seed dropped in sizzles instantly. Do not use a non-stick pan if you want a hard crust.
Lay the tuna steaks in the pan away from you. Sear undisturbed for 45 to 60 seconds, then flip with tongs and sear 45 to 60 seconds on the second side. The outside should be browned, the center still ruby.
Hold each steak on its edge for 10 seconds to render the sides, then transfer to a board. Pour the remaining soy-lime mixture into the hot pan, add the remaining 1 tsp soy sauce and the zest of the lime, and swirl for 20 seconds until it thickens slightly.
Slice the tuna against the grain into 1 cm strips, spoon the warm glaze over, and scatter with sliced spring onion and the juice of the remaining lime half. Serve immediately.
Kitchen notes
Kitchen notes
- The single biggest mistake is overcooking: tuna goes from ruby to grey in about 30 seconds. Pull it when the center still feels soft and springy when pressed, and remember it keeps cooking off the heat.
- Dry the surface and chill the steaks for 10 minutes before searing. A cold, dry exterior gives you a longer window to build crust before the middle cooks through.
- Do not marinate longer than 10 minutes. The soy and lime are acidic and will cure the surface, turning the flesh opaque and chalky.
- Use a cast-iron or carbon-steel pan and let it heat until the oil just begins to smoke. A lukewarm pan steams the sesame seeds instead of toasting them.
Substitutions
- honey→maple syrup or brown sugar
- soy sauce→tamari for a gluten-free version
- sesame oil→toasted peanut oil
- lime→lemon or yuzu juice
- neutral oil→grapeseed or avocado oil
Storage & reheating
Seared tuna is best eaten straight away, but leftovers keep in an airtight container in the fridge for up to 2 days. Do not freeze cooked tuna; the texture turns spongy. To reheat, warm gently in a dry pan over low heat for 30 to 40 seconds per side, or eat it cold flaked over rice or salad. Discard any tuna left at room temperature for more than 2 hours.
FAQ
The questions we get asked most
Can I use frozen tuna steaks for searing?
Yes, but thaw them fully in the fridge overnight, then pat them bone dry before cooking. Frozen-then-thawed tuna releases more water, so dry it twice and sear in a very hot pan. Never sear from frozen; the outside will overcook before the middle thaws.
How do I know when the tuna steak is done?
For rare, the center should still be translucent ruby and feel soft and springy when pressed with a finger. A 2.5 cm steak needs only 45 to 60 seconds per side over high heat. If the flesh turns pale pink all the way through, it is medium-well and will taste dry.
Why did my sesame crust fall off in the pan?
The steaks were probably wet or the pan was not hot enough. Pat the tuna dry, press the seeds on firmly, and let the oil shimmer before adding the fish. Do not move the steaks for the first 45 seconds so the seeds bond to the surface.
Can I marinate the tuna overnight?
No. The soy sauce and lime juice are acidic and will cure the outside of the fish, making it opaque and firm like ceviche. Ten minutes is the maximum; any longer and you lose the rare center you are searing for.
Is it safe to eat seared tuna rare?
Only if you buy sushi-grade or sashimi-grade tuna from a trusted fishmonger and keep it refrigerated until cooking. If you are pregnant, immunocompromised, or unsure of the sourcing, sear it to medium, about 2 minutes per side, until the center is pale pink.
What can I serve with seared tuna steak?
Steamed jasmine rice, soba noodles, or a crisp cucumber and radish salad all work well. The soy-lime glaze is salty and sharp, so keep sides plain and slightly acidic. Avoid heavy cream sauces, which overwhelm the delicate fish.
Can I cook seared tuna in an air fryer?
It is not recommended. Air fryers blow hot air and dry the sesame crust without giving the hard, fast sear that keeps the center rare. A cast-iron skillet or grill pan over high heat gives a far better result in the same amount of time.
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