In a large saucepan or rice cooker combine sushi rice and water and cook rice for 15-20 minutes. Remove from heat, emove lit and let it rest for 5 minutes.
Add rice vinegar to cooked rice and mix gently. Spread it out on the baking sheet to cool.
Separate evenly the rice in 5 or more bowls (depends how many colours you want) and mix it with the food colouring of your choice.
Place the sushi mat on a flat surface. Put a nori sheet on the top and add rice, one colour each time. Spread the rice evenly on the sheet, leaving about 0,5 cm around the edges. Dip your fingers in war water if needed.
Add vegetable of your choice and start rolling your sushi roll, pushing gently the vegetableinside the roll.
Repeat step 4 and 5 with each colour. Sprinkle your rolls with black sesame seeds.
Eat with tamari sauce, wasabi paste, and pickled ginger. Enjoy!