Peel, segment and place oranges in a medium bowl. Remove seeds carefully.
Peel and slice avocado, place in bowl, cover and refrigerate.
Tear lettuce leaves into bite size pieces, place in a large salad bowl. Arrange orange segments and avocado slices on top.
Chill for 1 hour and serve.
Method Note: How to segment an orange:
Start by slicing a small section about 1.5 cm (1/2 inch thick), from both top and bottom ends. With the fruit resting flat use a sharp knife to slice off the rind and the white pith.
Working over a bowl to catch the juice, slip the blade between the membrane and slice to the center, separating one side of the section. Turn the blade so that it is facing out and is lined up along the membrane of the opposite side of the section. Slide the blade from the center out along the membrane to free the section. Continue until all sections are removed.
Dressing Method: Combine all ingredients and whisk thoroughly. Refrigerate for an hour, then re-whisk before serving with salad.