Rinse and cook the jasmine rice: measure 120 g (about 2/3 cup) jasmine rice and rinse under cold water until the water runs mostly clear to remove excess surface starch—this prevents gummy rice. Combine the rinsed rice with 200 ml (about 3/4 cup + 1 tbsp) water in a small pot, cover, bring to a gentle simmer over medium heat, then reduce to the lowest heat and cook, covered, for 12 minutes. Turn off the heat and let rest, covered, for 8 minutes. Resting lets the steam finish cooking the rice evenly and produces separate, fluffy grains.

Prep the produce and dress the salad: while the rice cooks, peel and dice 180 g ripe mango and seed and dice 120 g cucumber into similar-size pieces for even texture. Thinly slice 2 scallions (white and green parts). In a medium bowl whisk together 2 tbsp soy sauce, 2 tsp sesame oil, 2 tsp rice vinegar, juice of 1 lime (about 2 tbsp), and if you like a touch of sweet balance, 1/2 tsp honey. Taste and adjust: the dressing should be bright, salty, and slightly sweet to complement the tuna. Toss the mango, cucumber, and scallions with the dressing and sprinkle 2 tsp sesame seeds, reserving a pinch for garnish.

Season and rest the tuna: pat the 280 g of ahi tuna steaks very dry with paper towels—moisture prevents a proper sear. Season both sides lightly with salt and freshly ground black pepper. Let the steaks sit at room temperature for 5–10 minutes while the pan heats; this promotes even cooking.

Heat the pan properly: use a heavy skillet (preferably cast-iron or stainless steel) and place it over medium-high heat. Add 1 tbsp neutral oil and heat until the oil is shimmering but not smoking. A properly hot pan is essential to develop a quick golden crust on the tuna without overcooking the interior.

Sear the tuna to desired doneness: place the tuna steaks in the hot pan and press gently so the surface contacts the pan. Sear for about 20–30 seconds per side for sushi-rare (just caramelized exterior, very rare center). For medium-rare, sear 45–60 seconds per side. Do the short edges for 10–15 seconds if steaks are thick. Searing at high heat creates a flavorful Maillard crust that contrasts the cool salad; quick cooking preserves the silky texture of ahi. Remove the tuna to a cutting board and let it rest 2 minutes—resting lets juices redistribute.

Slice the tuna and assemble: with a sharp knife, slice the tuna against the grain into 6–8 thin slices per steak (thin slices make each bite tender). Fluff the rice with a fork and divide between two bowls. Spoon the mango-cucumber-scallion salad over the rice. Fan the sliced tuna across each bowl, sprinkle remaining sesame seeds and an extra drizzle of soy (or reserved dressing) if desired. Finish with an extra squeeze of lime and a crack of black pepper.

Serve immediately: serve while the tuna is still warm at the edges and the rice is warm—the contrast of warm rice and seared fish with cool, bright salad is central to the dish’s appeal.