Rinse the sushi rice under cold water until the water runs clear. Drain well.
In a medium pot, combine the rinsed rice and water. Bring to a boil over medium heat. Once boiling, reduce heat to low, cover, and simmer for 15 minutes. Remove from heat and let it sit, covered, for another 10 minutes.
In a small bowl, mix rice vinegar, sugar, and salt. Heat in the microwave for 20 seconds or until the sugar dissolves.
Once the rice is ready, fluff it with a fork and gently mix in the vinegar mixture. Allow the rice to cool.
Place a bamboo sushi mat on a clean surface and lay a sheet of nori on top, shiny side down.
Wet your hands to prevent sticking, then take about 1/4 of the sushi rice (approximately 1/2 cup) and evenly spread it over the nori, leaving a 1-inch border at the top.
Arrange a line of cucumber, carrot, avocado, bell pepper, and radish along the center of the rice-covered nori.
Starting from the bottom, use the sushi mat to gently roll the nori away from you, applying light pressure to form a tight roll. Seal the edge with a little water.
Use a sharp knife to slice the sushi roll into 6-8 pieces. Wipe the knife with a damp cloth between cuts for cleaner slices.
Sprinkle sesame seeds on top of the sushi rolls for garnish.
Notes
Serve on a bamboo platter with soy sauce for dipping. Garnish with pickled ginger and wasabi for added flavor.