Rinse 2 cups sushi rice under cold water until the water runs mostly clear (about 3–4 rinses). Drain. Combine rinsed rice and 2.25 cups water in a medium saucepan. Bring to a boil over medium-high heat, then reduce heat to low, cover, and simmer 15 minutes. Remove from heat and let rest, covered, 10 minutes.

Season rice

While rice rests, warm 3 tablespoons rice vinegar, 1.5 tablespoons sugar, and 1/2 teaspoon salt in a small saucepan (or microwave) just until sugar dissolves. Transfer rice to a shallow bowl, drizzle seasoning over rice, and gently fold with a rice paddle or spatula to combine and slightly cool. Fan or let sit uncovered 5–10 minutes until slightly warm or room temperature.

Spicy Tuna

Prepare tuna

Keep tuna cold. Trim and dice 12 oz sashimi-grade tuna into 1/2-inch cubes. Place in a bowl.

Make spicy mix

In a small bowl, combine 3 tablespoons mayonnaise, 1 tablespoon sriracha, 1 teaspoon soy sauce, and 1/2 teaspoon toasted sesame oil. Taste and adjust heat or salt as desired. Add 1 teaspoon toasted sesame seeds and mix.

Toss sauce with tuna just before assembling so the fish stays firm: add the spicy mayo mixture to the diced tuna and fold gently until evenly coated. Refrigerate while assembling bowls if not serving immediately.

Vegetables & Add-ins

Prepare veggies

Thinly slice watermelon radish to yield about 1 cup; thinly slice cucumber into half-moons; thinly slice 1/2 jalapeño (remove seeds if you prefer milder heat). If using frozen edamame, steam or boil for 3–5 minutes until tender, then drain and cool. Dice the avocado just before assembly and toss gently with a squeeze of lime to slow browning.

Sauces & Finishes

Make sriracha mayo (if making)

If not using store-bought, whisk together 3 tablespoons mayonnaise and 1 tablespoon sriracha (adjust to taste) until smooth. Transfer to a squeeze bottle or small bowl for drizzling.

Warm sweet chili teriyaki (optional)

If your sweet chili teriyaki sauce is thick or chilled, warm briefly in a small saucepan or microwave (10–15 seconds) so it drizzles easily.

Assemble bowls: divide the seasoned sushi rice between 3–4 bowls (about 1 to 1 1/3 cups rice per serving). Top each bowl with an equal portion of spicy tuna (about 3–4 oz), watermelon radish slices, cucumber, edamame, diced avocado, and jalapeño slices.

Drizzle 1 tablespoon sweet chili teriyaki and about 3/4 tablespoon sriracha mayo over each bowl (adjust amounts to taste). Garnish with sliced scallions, a sprinkle of furikake or toasted sesame seeds, pickled ginger if using, and lime wedges on the side.

Serve immediately so tuna is chilled and rice is slightly warm. Provide extra sriracha mayo and sweet chili teriyaki on the side for guests to add more heat or sweetness.