Keep the tuna very cold. Pat dry with paper towels. Trim any sinew and cut into 1/4-inch dice. Place diced tuna into a chilled bowl. Season with 1/2 tsp fine sea salt and 1/4 tsp freshly ground black pepper; gently toss to combine. Return to refrigerator while you prepare other components.

Dressing & Seasoning

Make dressing

In a small bowl whisk together 2 tbs soy sauce, 1 tsp toasted sesame oil, 1 tsp rice vinegar, 1 tbs fresh lime juice, 1 tsp mirin (if using), 1 tsp grated fresh ginger, 1/2 tsp minced garlic, 1/2 tsp Sriracha, and 1/2 tsp honey. Taste and adjust balance — it should be savory with a bright acidic note and a touch of heat.

Dress the tuna

Pour about three-quarters of the dressing over the diced tuna and gently fold to coat evenly, being careful not to mash the cubes. Reserve the remaining dressing for the avocado and to finish the tower. Chill tuna for 5–10 minutes to let flavors marry (do not marinate longer than 20 minutes to preserve texture).

Crunch & Binder

Prepare mix-ins

Gently fold the diced avocado, 2 tbsp sliced green onions, 1/2 cup seeded diced cucumber, 1 tsp toasted sesame seeds, and 1 tbsp chopped cilantro into the dressed tuna. Use a light hand so avocado keeps some shape. If mixture seems too loose, add an additional 1/2 tsp sesame oil or a touch more mayo (from the Accompaniments section).

Assemble Tower

Shape tartare towers

Use a 2.5–3 inch round ring mold or a cleaned food ring. Place the ring on chilled serving plates. Spoon a layer (about half) of the tuna-avocado mixture into the bottom of the ring and press gently and evenly to create a compact base. Add a thin layer (1–2 tbsp) of wasabi mayo across the center if making a stacked ‘tower’ with a second layer of tuna; otherwise, place remaining tuna mixture on top and press lightly to form a neat tower. Carefully lift the ring straight up to release the tower.

Alternate stacking option

For a composed tower, first layer a thin bed of microgreens inside the ring, then add half the tuna mix, a smear of wasabi mayo, and top with remaining tuna mix. This gives height and visual contrast.

Accompaniments & Garnish

Garnish and finish

Drizzle a few drops of reserved dressing and 1/2 tsp toasted sesame oil lightly over the tower. Sprinkle a few extra toasted sesame seeds and a pinch of sliced green onion on top. Arrange microgreens and pickled ginger beside the tower. Place 3–4 toasted baguette slices or 3–4 wonton crisps around the plate for scooping. Add a lime wedge to the plate for guests to squeeze.

Wasabi mayo (optional)

Combine 3 tbs mayonnaise with 1/2–1 tsp wasabi paste (adjust to heat preference). Whisk until smooth. Place a small quenelle or smear on the plate or pipe a small dot on top of the tower before serving.

Serve

Serve immediately while tuna is cold and avocado is fresh. Recommend serving within 10–15 minutes of assembly for best texture and presentation.