Mix the vinegar with the sugar and set aside. Tip the rice and kelp into a small non-stick pan with 300ml water. Cover and cook over a low heat for 20 mins until tender. Remove the lid and cook for 3-5 mins more, so the excess water evaporates. Be careful not to let it catch on the base of the pan. Stir in the vinegar mixture, then carefully spread out on a plate to cool at room temperature.

When the rice is cool, shape into an oblong, then divide into 12 equal portions. With wet hands, take a portion of rice, put it in the palm of your hand and squeeze together quite tightly so that it forms a little cylinder that sticks together. Repeat with the remaining rice. Top each rice cylinder with a slice of avocado, then wrap with a strip of smoked salmon. Scatter with sesame seeds, then serve with the wasabi, sushi ginger and tamari.