Clean the lettuce and cut into bite-sized pieces. Peel the red onion and cut into rings. Halve the avocado, remove the stone, cut the pulp into wedges and drizzle with 2 tablespoons of lemon juice. Dice the tomato and mix the salad ingredients.
Then mix the oil, vinegar, salt, pepper and sugar together for the dressing. Finally, distribute the salmon on the salad and drizzle with the dressing.