Seared Ahi Tuna Recipe

Slice vegetables

Trim the cucumber ends and very thinly slice the cucumber (use a mandoline or a sharp knife) into 1/16–1/8 in (1.5–3 mm) rounds. Peel the red onion and slice very thinly into half-moons. Place cucumber and onion in a medium bowl.

Make pickling liquid

In a small bowl or measuring cup combine rice vinegar, water, sugar, kosher salt, sesame oil, and red pepper flakes. Stir until the sugar and salt are dissolved.

Pickle

Pour the pickling liquid over the cucumber and onion, toss to coat. Let sit at room temperature for 15–20 minutes to quick-pickle (or cover and refrigerate for up to 2 hours for milder flavor). Drain slightly before plating, reserving a tablespoon of pickling liquid for the sauce if desired.

Combine sauce ingredients

In a small bowl whisk together soy sauce, Dijon mustard, toasted sesame oil, lime juice, honey, minced garlic, and freshly ground black pepper until smooth and slightly emulsified. Taste and adjust balance — add another 1/2 tsp honey if you prefer sweeter, or a few drops more lime for brightness.

Prepare tuna

Pat the tuna dry with paper towels. Season all sides lightly with kosher salt and freshly ground black pepper.

Sear

Heat a heavy skillet or cast-iron pan over high heat until very hot (about 2–3 minutes). Add the neutral oil and swirl to coat. Carefully place the tuna in the pan and sear for 30–45 seconds per side for rare center (adjust to 60–75 seconds per side for medium-rare). Use tongs to sear the edges briefly so all sides get a thin crust. Total cook time should leave the interior pink/translucent.

Rest and slice

Remove tuna from the pan and transfer to a cutting board. Let rest for 2 minutes, then slice against the grain into 1/4 in (6 mm) thick slices.

Arrange 6–8 slices of seared ahi on chilled plates or a single serving plate. Spoon a small mound of pickled cucumbers and onions alongside or on top of the fish.

Drizzle the soy mustard sauce over the tuna slices and a little around the plate for presentation. If you reserved a tablespoon of pickling liquid, whisk a drop into the sauce to tie flavors together before drizzling.

Finish with a sprinkle of toasted sesame seeds, sliced scallions, and microgreens or cilantro. Serve immediately.