For each roll, spread about 125 ml (1/2 cup) of rice on the dull side of the nori, 4-cm (1 ½-inch) from the edge of the narrow side; work with moistened fingers. Flip the sheet for the rice to be on the underside. Spread about 15 ml (1 tablespoon) of spicy mayonnaise in the centre of the sheet. Top with julienne cucumber, overhanging on each side. Add two pieces of crab cake, some carrots and avocado.