TUNA STEAK with Sesame Crust and Ponzu
Tuna does not need much. That is the point.
A good piece of sashimi-grade yellowfin or bigeye tuna is one of the finest things you can cook over fire. The sesame crust gives it texture and a deep, nutty char. The centre stays rare, cold almost, and the contrast between the two is what makes this dish. The ponzu cuts through the richness of the sesame with citrus and umami in equal measure.
The cook is fast. Two minutes per side over screaming hot coals or a cast iron pan on the BBQ. The preparation takes longer than the cooking. Get everything ready before the tuna goes near the heat. Once it is on, there is no time to find anything.
Buy the best tuna you can find. Sashimi-grade from a fishmonger is the standard here. Supermarket tuna will work but the result will not be the same. This recipe rewards quality ingredients.
AT A GLANCE
Serves 2
Prep Time 20 minutes (plus 30 minutes marinating)
Cook Time 4 to 5 minutes
Fire Setup Direct high heat, cast iron or grill grate
Surface Temp 250 degrees C or higher
Target Internal Rare: cool red centre (45 to 50 degrees C)
Difficulty Easy to moderate
INGREDIENTS: THE TUNA
2 x 200 g Sashimi-grade tuna steaks, at least 3 cm thick
2 tbsp White sesame seeds
2 tbsp Black sesame seeds
1 tsp Flaky sea salt
1 tsp Cracked black pepper
1 tbsp Neutral oil (for the pan or grate)
INGREDIENTS: PONZU SAUCE
3 tbsp Soy sauce (light or tamari for gluten free)
2 tbsp Fresh yuzu juice (or equal parts lemon and lime juice)
1 tbsp Mirin
1 tsp Rice wine vinegar
1 tsp Sesame oil
1 tsp Fresh ginger, finely grated
1 Spring onion, finely sliced
INGREDIENTS: TO SERVE
1 Long red chilli, finely sliced
2 Spring onions, finely sliced on the diagonal
1 tbsp Pickled ginger
Micro herbs or shiso leaves (optional)
Steamed rice or soba noodles to serve alongside
METHOD
01. MAKE THE PONZU
Combine the soy sauce, yuzu juice (or lemon and lime), mirin, rice wine vinegar, sesame oil, grated ginger, and sliced spring onion in a small bowl. Stir well and set aside. The ponzu improves as it sits, so make it first and allow the flavours to come together while you prepare everything else.
Taste the ponzu before serving. It should be sharp, salty, and slightly sweet. Adjust with more citrus or mirin to balance.
02. PREPARE THE SESAME CRUST
Combine the white and black sesame seeds, flaky salt, and cracked pepper on a flat plate or board. Mix together and spread into an even layer. The crust needs to be thick enough to coat all four sides of the tuna steak completely.
Using both white and black sesame seeds is not just visual. They have slightly different flavour profiles and the contrast reads well on the plate.
03. COAT THE TUNA
Pat the tuna steaks completely dry with paper towel. Press each steak firmly into the sesame mixture on all four sides and the two ends, pressing the seeds in with your palm to ensure they adhere. The tuna should be fully coated. Set aside on a clean board for 10 minutes before cooking.
Dry tuna is essential. Any moisture on the surface will steam the sesame crust rather than sear it, and the seeds will fall off.
04. GET THE HEAT RIGHT
This cook requires the highest heat you can produce. For a kettle BBQ, bank all coals directly under the grate and allow it to preheat for 5 minutes. For a cast iron pan on the BBQ, heat it directly over the coals until it begins to smoke. Add a thin film of neutral oil just before the tuna goes in. The oil should shimmer and almost smoke on contact.
There is no middle ground here. Insufficient heat means the sesame crust steams and the tuna overcooks before you get any colour.
05. SEAR THE TUNA
Place the tuna steaks onto the hot surface. Sear for 60 to 90 seconds per side without moving. You are cooking four sides in total. The sesame crust should be deep golden and fragrant on each face. The centre must remain rare. Total cook time should not exceed 5 minutes for a 3 cm steak. Remove from heat immediately.
Watch the sides of the steak as it cooks. When the colour change reaches 5 mm up from the bottom, it is time to turn.
06. REST BRIEFLY, THEN SLICE
Rest the tuna for 60 seconds only. Unlike red meat, tuna does not benefit from a long rest and will continue to cook if left. Using your Classic Bunka, slice the tuna against the grain into 1 cm slices with a single, clean drawing motion. The flat profile and acute tip of the Bunka give you the control to cut through the sesame crust cleanly without shattering it.
One clean draw per slice. Do not press down or saw. Let the blade do the work.
07. PLATE AND SERVE
Arrange the sliced tuna on a board or plate, fanning the slices slightly to show the rare centre. Spoon the ponzu generously over the top. Finish with finely sliced chilli, spring onion, and pickled ginger. Add micro herbs or shiso leaves if available. Serve immediately with steamed rice or cold soba noodles alongside.
Serve within two minutes of slicing. Tuna at room temperature loses its appeal quickly.
SERVE WITH
Steamed jasmine rice or cold soba noodles dressed with sesame oil and rice vinegar. Edamame with flaky salt. Sliced cucumber with a light rice vinegar dressing. Cold Japanese lager or a dry, unoaked Chardonnay. Keep the sides clean and simple so the tuna stays the focus.
THE RIGHT KNIFE
Two knives earn their place at this cook. The Outsider Chef Knife handles the prep work: grating ginger, slicing spring onion and chilli, and anything else that needs a fast, capable blade at the fire. The Classic Bunka is the slicing knife. Its flat profile and acute tip are purpose-built for clean, precise cuts through fish. A single drawing motion through the sesame crust with no pressure, no sawing, and no shattered seeds. It is the right tool for the job.
