Keep the bluefin tuna well chilled. Using a very sharp knife, slice the tuna into 1/8–1/4-inch (3–6 mm) thin slices or into small bite-size cubes depending on presentation. Place sliced or cubed tuna on a chilled tray and lightly season with 1/2 tsp fine sea salt and 1/4 tsp black pepper, then drizzle 2 tbsp extra-virgin olive oil and 1 tbsp lemon juice evenly. Gently toss to coat. Refrigerate until ready to plate (no more than 10–15 minutes).

When assembling, arrange tuna portions on chilled plates, leaving space for compressed cucumber and olive textures. Drizzle a small amount of shio koji dressing around the fish (about 1/2 tsp per portion) and finish with microgreens, toasted sesame seeds and a light dusting of lemon or yuzu zest.

Compressed Cucumbers

Quick compress

Peel cucumber lengthwise if skin is waxy; otherwise leave skin for color. Using a mandoline or very sharp knife, slice cucumber into 1/8-inch (3 mm) rounds. In a bowl, dissolve 1 tsp sugar and 1/2 tsp salt into 2 tbsp rice vinegar + 3 tbsp cold water. Add the cucumber slices and toss to coat. Layer the cucumber in a shallow container or vacuum bag for better compression: press firmly with a flat weight (or vacuum-seal and remove air). Add a handful of ice into the container around (not on) the cucumber to keep very cold if not vacuuming. Let compress for 20–30 minutes; the slices will release liquid and take on the pickling flavor while staying crisp. Drain well and pat dry before plating.

Shio Koji Dressing

Mix dressing

In a small bowl whisk together 2 tsp shio koji, 1 tsp neutral oil, 1/2 tsp mirin, 1 tsp lime juice and 1/2 tsp lime zest until homogenous. Taste and adjust: shio koji brings saltiness and umami, so add an extra 1/4 tsp if you prefer more seasoning. Stir in 1 tbsp finely sliced chives. Keep chilled until plating. Use this dressing sparingly on the tuna and cucumbers (about 1 tsp per two portions).

Olive Textures

Olive oil infusion / gel

For a smooth olive oil texture: blend 1/2 cup extra-virgin olive oil with 1/4 cup pitted kalamata and 2 tbsp pitted green olives in a blender until smooth. Taste and pass through a fine mesh to remove solids. If you want a slightly thicker 'gel', warm the strained olive puree gently and whisk in 1 tsp cornstarch dissolved in 1 tsp cold water; bring to a very gentle simmer until it thickens slightly, then cool — this yields an oil-based emulsion/gel. Keep chilled.

Olive powder / crumble

For an olive powder: spread remaining blended olive solids thinly on a parchment-lined tray and dry in a low oven (about 150°F / 65°C) or dehydrator until crumbly (1–2 hours). When dry, pulse in a food processor with 1 tsp cornstarch until sandy. This creates a salty olive crumble to scatter over the dish for texture.

Olive foam (optional)

If you have soy lecithin: strain 1/4 cup blended olive liquid into a bowl, sprinkle 1/2 tsp soy lecithin, then use an immersion blender to create a stable foam. Spoon foam onto plates immediately before serving. Alternatively, use the olive gel for a cleaner presentation.

Garnish & Finish

Plate: place a small mound or rings of compressed cucumber on each plate. Arrange tuna slices or cubes atop or beside the cucumber. Dot the olive gel around and sprinkle olive crumble for contrast. Add a few drops of shio koji dressing around the fish and a light drizzle of extra-virgin olive oil if desired. Finish with microgreens, toasted sesame seeds, and a final burst of lemon or yuzu zest. Serve immediately while tuna is cold and fresh.