Place sushi rice into a bowl and rinse until the water runs clear.
Cover the rice with cold water and leave to soak for 15-30 minutes.
Drain the rice and add to a small saucepan along with the water.
Bring the rice to the boil, reduce the heat and simmer gently with the lid off for 10 minutes.
Turn the heat off, pop the lid on the saucepan and leave the rice to steam in the pan for a futher 10 minutes.
Meanwhile, place the vinegar, caster sugar and salt into a small jar and shake until dissolved.
When the rice has finished cooking, transfer it to a bowl and gently fold in the vinegar seasoning.
Cover the bowl with a damp tea towel and leave the rice to cool to room temperature, about half an hour.
Place a small square of clingfilm onto your bamboo mat. Arrange a sheet of nori seaweed in the centre.
Spoon 1/3 of the cooled rice onto the nori seaweed and, using wet fingertips, spread the rice to the edges of the seaweed. Leave a 1 cm gap at the top.
Sprinkle the rice with sesame seeds.
Turn the seaweed and rice over, so that the sesame seeds are face down on the clingfilm.
Using your bamboo mat, roll up the seaweed and rice to form a sushi roll.
Cover the outside of the sushi roll with slices of smoked salmon.
Wrap in clingfilm, and repeat with the remaining seaweed and rice.
Chill the sushi rolls until needed. This can be made a day in advance.
Using a sharp knife, cut each sushi roll into 8 pieces.
Garnish with a sprig of dill and a small spoonful of black lumpfish caviar.