1. Lay one sheet of nori, shiny side down, on a bamboo sushi mat or clean dish towel. Using the back of a teaspoon, spread 1 teaspoon of the miso in a single horizontal strip anywhere along the bottom third of the nori. Along the edge of the nori closest to you, layer half of the sprouts, avocado, cucumber, carrot, and bell pepper.
2. To roll, grip the edges of the nori sheet and the sushi mat/dish towel together with your thumbs and forefingers, and press the filling back toward you with your other fingers. Using the mat to help you, roll the front edge of the nori over the filling. Squeeze it with the mat/towel; then lift the mat/towel and continue rolling.
3. Just before completing the roll, dip your index finger in water and run it along the far edge of the nori sheet. This will seal the seam of the roll. Cut the roll into 6 pieces with a sharp knife.