Follow these detailed, step-by-step instructions carefully to ensure your homemade sushi-making experience is a success. We will break the process down into manageable stages: preparing the rice, prepping the fillings, and finally, the art of rolling and slicing.

Part 1: Mastering the Perfect Sushi Rice

The foundation of any great sushi roll is the rice. This step is the most time-consuming but arguably the most important. Do not rush it.

1. Rinse the Rice: Place the 2 cups of sushi rice into a large bowl. Cover it with cold water and use your hands to gently swish and massage the rice. The water will become milky and cloudy. Carefully pour out the cloudy water, using a fine-mesh sieve if needed to prevent losing any rice grains. Repeat this process 4-5 times, or until the water runs mostly clear. This step is non-negotiable; it removes the excess surface starch, which prevents the rice from becoming a gummy, pasty mess. Drain the rice thoroughly in the sieve for at least 15 minutes.
2. Cook the Rice: Transfer the drained rice and the 2 ¼ cups of fresh water to a medium saucepan with a tight-fitting lid. Bring the water to a boil over medium-high heat. Once it’s boiling, immediately reduce the heat to the lowest possible setting, cover the pot with the lid, and let it simmer for exactly 15 minutes. Do not lift the lid during this time.
3. Rest the Rice: After 15 minutes, remove the saucepan from the heat, but keep the lid on. Let the rice steam, undisturbed, for another 10-15 minutes. This allows the moisture to distribute evenly throughout the grains, resulting in a perfectly fluffy texture.
4. Prepare the Vinegar Seasoning: While the rice is resting, combine the ¼ cup of rice vinegar, 2 tablespoons of sugar, and 1 teaspoon of salt in a small, non-reactive bowl or saucepan. Gently warm the mixture over low heat or in the microwave for 30-45 seconds, stirring until the sugar and salt have completely dissolved. Set this aside.
5. Season the Rice: Transfer the hot, cooked rice to a large, non-metallic bowl (a wooden, glass, or plastic bowl works best, as metal can react with the vinegar). While the rice is still hot, slowly drizzle the vinegar mixture all over it. Using a wooden spoon or rice paddle, gently “cut” and “fold” the seasoning into the rice with slicing motions. Avoid stirring or mashing the rice, as this will break the grains and make it mushy. The goal is to coat each grain without crushing it.
6. Cool the Rice: Fan the rice while you are folding it to help it cool down to room temperature more quickly and to give it a beautiful, glossy sheen. You can use a hand fan, a piece of cardboard, or simply let it cool naturally. Cover the bowl with a damp cloth to prevent the surface from drying out while you prepare the other ingredients.

Part 2: Preparing the Fresh Fillings

With the rice cooling, it’s time to prep the crisp and creamy fillings.

1. Prepare the Cucumber: Wash and dry the English cucumber. Trim off the ends. Using a sharp knife, slice the cucumber in half lengthwise. If there are a lot of seeds, you can use a small spoon to gently scrape them out. Lay the cucumber halves flat-side down and slice them lengthwise into long, thin matchsticks (julienne).
2. Prepare the Avocado: Slice the avocados in half lengthwise and remove the pits. Carefully peel the skin off each half. Place the avocado halves flat-side down on your cutting board and slice them into ¼-inch thick strips. To prevent browning, you can very lightly spritz them with lemon or lime juice.

Part 3: The Art of Assembling and Rolling

This is the fun part! Set up your sushi-making station with your bamboo rolling mat (makisu), a small bowl of water, your cooled sushi rice, the nori sheets, and your prepared fillings.

1. Set Up Your Mat: Place your bamboo mat on a clean, flat work surface. Many people find it helpful to wrap the mat in plastic wrap for easy cleanup and to prevent rice from sticking to it.
2. Place the Nori: Lay one sheet of nori, shiny-side down, on the bamboo mat. The rougher side should be facing up, as it helps the rice adhere better. Align the bottom edge of the nori with the bottom edge of the mat.
3. Spread the Rice: Dip your fingers into the small bowl of water to prevent the rice from sticking to them. Take a handful of sushi rice (about ¾ to 1 cup) and gently spread it over the nori. Start from the center and work your way out, creating a thin, even layer. Leave a 1-inch border of bare nori at the top edge, away from you. This empty space is crucial for sealing the roll. Be gentle and use your fingertips to press, not mash, the rice.
4. Add the Fillings: About one-third of the way up from the bottom edge of the rice, arrange a horizontal line of your fillings. Place a few strips of cucumber and a few slices of avocado in a neat row across the rice. If using, sprinkle a pinch of toasted sesame seeds over the fillings. Be careful not to overfill the roll, as this is the most common reason for rolls bursting or being difficult to roll.
5. Roll it Up:
   • The Tuck: Lift the bottom edge of the bamboo mat (along with the nori and rice) and carefully fold it over the fillings. Use your fingers to tuck the fillings in tightly as you roll. The edge of the nori should tuck just past the fillings.
   • The Roll: Squeeze the roll gently but firmly with the mat to compact the ingredients and form a tight cylinder. Continue to roll forward, lifting the edge of the mat as you go so it doesn’t get rolled into the sushi.
   • The Seal: When you reach the bare 1-inch strip of nori at the top, dip your finger in the bowl of water and lightly dampen the nori. This will act as an adhesive. Complete the roll, and the damp edge will seal it shut.
6. Firm the Roll: Once rolled, you can use the bamboo mat to gently press and shape the roll one more time to ensure it’s a uniform, compact cylinder.

Part 4: Slicing and Presenting

A clean slice is the final touch for professional-looking sushi.

1. Prepare Your Knife: Take your sharpest knife (a long, thin blade is best). Dip the blade into your bowl of water or wipe it with a damp cloth before each and every cut. A wet blade is the secret to slicing through the roll without tearing the nori or squishing the fillings.
2. Slice the Roll: Place the completed sushi roll on a cutting board. First, slice the roll directly in half. Then, place the two halves side by side and slice them both into three or four equal pieces, resulting in 6 or 8 bite-sized sushi pieces per roll.
3. Repeat and Serve: Repeat the rolling and slicing process with the remaining nori sheets and fillings. Arrange your beautiful Cucumber Avocado Vegetarian Sushi Rolls on a platter and serve immediately.