Step 1

Place rice and water in a saucepan over high heat, bring to a boil, and reduce heat to very low. Cover with a tight-fitting lid and simmer rice until water is absorbed, about 15 minutes. Remove rice from heat and allow to stand covered for 10 minutes.

Step 2

Mix red wine vinegar, sugar, and salt in a bowl until sugar has dissolved. Fluff rice with a fork and transfer into a large bowl; pour vinegar mixture into the rice and stir to coat rice. Spread rice out onto a large piece of parchment paper and fan the rice until cool. Cover rice with damp paper towels.

Step 3

Sprinkle avocado slices with lemon juice in a bowl.

Step 4

Spread a thin layer of sesame seeds onto a sushi mat. Pick up about half a cup of cooled rice and place onto sushi mat in an even layer. Place 1/4 of the cucumber, avocado slices, bell pepper, and zucchini in a line down the middle of the rice.

Step 5

Pick up the edge of the sushi mat, fold the bottom edge of the sheet up, enclosing the filling, and tightly roll the sushi into a thick cylinder. Once the sushi is rolled, wrap it in the mat and gently squeeze to compact it tightly. Repeat with remaining ingredients to made 4 rolls. Place rolls on a serving plate, slice into 6 or 8 pieces per roll, and cover with damp paper towels until serving time.