Salmon-Avocado Cucumber Sushi Boats

1. Rinse rice in a sieve under cold water until water runs clear, about 1 minute. Bring rice and water to a boil over medium-high heat in a saucepan. Reduce heat to medium; simmer, covered, until rice is tender and water is absorbed, about 15 minutes.
   

2. Meanwhile, whisk together vinegar, sugar, and salt in a small bowl until sugar and salt dissolve. Drizzle vinegar mixture over hot rice; gently fold in. Cover surface of rice with a damp paper towel; let cool to room temperature, about 1 hour.
   

3. Halve cucumbers lengthwise, then cut each half crosswise into 4 equal pieces (for a total of 16 pieces). Trim a thin slice from the peel side of each piece (so the pieces will sit flat). Scoop out seeds from each piece, leaving a 1/3-inch border. Spoon 1 to 11/2 Tbsp. rice into each cucumber piece, then use damp hands to compact rice. Top each with salmon and avocado. Sprinkle with sesame seeds.
   

4. Serve with soy sauce, furikake, Kewpie mayonnaise, wasabi, and/or ginger.

Cook's Note:

Look for specialty toppings like furikake or Kewpie mayonnaise in the international section of the grocery store or at an Asian market. 

Variations:

Spicy Crab

Prep as directed, topping rice-packed cucumber pieces with chopped crabstick tossed with purchased yum yum sauce. Serve as directed.

Yellowtail-Jalapeño

Prep as directed, topping rice-packed cucumber pieces with thinly sliced sushi-grade yellowtail tuna, yuzu sauce, and thinly sliced jalapeños. Serve as directed.

Shrimp and Mango

Prep as directed, topping rice-packed cucumber pieces with sliced fresh mango and cooked peeled shrimp. Serve as directed.