Rinse the sushi rice several times with water until the water remains clear. Then soak the sushi rice in water for 30 minutes.
Gently simmer the rice with 350 ml (1.4 cups) water for 10-15 minutes. Remove the pot from the stove and place a damp kitchen towel between the pot and the lid. Let the sushi rice swell for another 15-20 minutes.
Pour sushi rice into a wooden bowl. Mix rice vinegar, agave syrup and a generous pinch of salt and work it into the sushi rice with a wooden spatula. Cover the sushi rice and let it swell for another 20 minutes with a damp kitchen towel.
Cut avocado and vegetables into fine strips. Wash the cilantro and shake dry.
Wrap a sushi mat with cling film. Place half a (!) nori algae leaf with the shiny side down on the prepared sushi mat. With moistened hands, place a portion of rice on the algae leaf and press flat in a rectangular shape, filling the nori leaf completely. Sprinkle rice with 1/2 teaspoon black sesame seeds and press sesame seeds with wet hands. Carefully turn the nori leaf with the rice on the sushi mat (see video below for more details)
Place the avocado, cilantro, red cabbage, carrot and pepper strips in the middle of the shiny side of the nori leaf and use the sushi mat to form a compact roll.
Cut the sushi roll into pieces with a very sharp, moistened knife.
