Rinse the rice in a sieve until the water runs clear. Drain and put in a large pan with 400ml water. Bring to the boil, turn the heat to low, cover, then cook for 10-12 mins until the rice is almost cooked. Remove from the heat, then leave, covered, for another 10 mins.
Thinly slice the salmon and arrange on a platter with the sliced avocado. Drizzle over the lemon juice and soy, making sure everything is evenly covered. Leave in the fridge to marinate for 10 mins.
Carefully tip the juices from the salmon platter into the rice, then stir in with a little salt. Divide the rice between 4 bowls. Scatter the sesame seeds, spring onions, chilli and coriander over the salmon and avocado, then serve with the rice.