1) Pull the lettuce leaves from the head, rinse gently under cold water and lay out on clean towels to dry. Use a spoon to remove the flesh in one piece from each half of the avocado. Slice the avocado flesh into thin wedges.
2) Arrange the lettuce leaves on a plate and top with the avocado wedges, spring onions and coriander.
3) Finish with a healthy drizzling of the dressing and serve.
Dressing: Whisk together all the dressing ingredients.