Veggie Sushi Rolls

INGREDIENTS

• cooked sushi rice 1 1/4 cups (6 oz/185 g)
• English cucumber 1/4, peeled and cut into thin matchsticks
• carrot 1/2, peeled and cut into thin matchsticks
• unseasoned rice vinegar 1 teaspoon
• toasted nori seaweed 1 sheet, about 7 by 8 inches (18 by 20 cm)
• toasted sesame seeds 1 tablespoon, plus more for sprinkling
• soy sauce and pickled ginger slices for serving (optional)
• ripe avocado 1/4, thinly sliced