Homemade Sushi Rolls

• Put rice into a large deep bowl. Fill with cold water and rub rice together with hands until water turns milky white. Drain cloudy water, being careful not to pour out rice. Repeat three or four times until you can see rice through 3 inches of water; drain once more.
• Transfer rice to a saucepan; add kombu and 3 cups water. Let stand 30 minutes. Cover; bring to a boil over high heat. Reduce heat to low; simmer 10 minutes. Remove from heat and let stand, covered, 5 minutes.
• Meanwhile, stir together rice vinegar, sugar, and salt in a small bowl until dissolved.
• Remove and discard kombu; stir in vinegar mixture until no lumps remain. Spread rice mixture onto a rimmed 9×13 baking sheet. [Spreading helps cool rice and prevents it from continuing to cook.] Let cool to room temperature.
• Lay one sheet of nori on a sushi mat lined with plastic wrap; spread 1 cup of rice over nori with damp fingers, leaving a 1-inch border along one edge. Arrange desired fillings (see below) crosswise just off center of rice. Carefully lift filled edge of nori and roll over filling toward unfilled edge, tucking as you roll. Brush unfilled edge of nori with water; press to seal. Cut each roll into 8 pieces. Repeat with remaining nori, rice, and fillings. To make ahead, chill, covered, up to 4 hours.

Philadelphia Roll

• Trim and quarter half a cucumber. Thinly slice each quarter lengthwise to make 8 spears. Cut 4 oz. cream cheese into 4 sticks. After spreading rice on nori (do not leave a border), sprinkle each roll with 1 tsp. each white sesame seeds and black sesame seeds. Carefully flip over. Arrange 2 oz. cold smoked salmon, the cucumber, and cream cheese sticks in a line across the sheet about one-third from the top. Roll and cut as directed. Makes 4 rolls.

California Roll

• Trim and quarter half a cucumber. Thinly slice each quarter lengthwise to make 8 spears. Slice 1 avocado into 8 slices. Trim 31/2 oz. imitation crab (surimi) into 4 sticks. Evenly arrange cucumber, avocado, and crab in a line on rice about one-third of the way from tops of rice. Layer each roll with 2 cucumber spears and 2 slices avocado. Roll and cut as directed. Makes 4 rolls.

Spicy Tuna Roll

• Trim and quarter half a cucumber. Thinly slice each quarter lengthwise to make 8 spears. Slice 1 avocado into 8 slices. Very thinly slice 1 small carrot lengthwise to get 1/2 cup matchsticks. Stir together 1 (5-oz.) can solid white tuna in water, drained; 1 Tbsp. mayonnaise; 1 tsp. wasabi paste; and 1/2 tsp. chile-garlic paste in a small bowl. Evenly arrange carrot, cucumber, and avocado in a line on rice across the sheet about one-third from the top. Spread a line of tuna alongside vegetables. Roll and cut as directed. Makes 4 rolls.