Citrusy, creamy, zesty and rich all in one salad.
In a small bowl, mix the vinaigrette ingredients.
To supreme the grapefruit, first slice off a half-inch or more from the stem end and the blossom end of the fruit, enough to easily expose the fruit. Use a sharp knife. Then use the knife to cut away the peel from the grapefruit, following the contours of the fruit. Keep cutting away the peel until the grapefruit is completely peeled.
Use the knife to cut alongside the membranes that separate the grapefruit segments. Remove the segments by either cutting the segments away from the membranes, or by gently pulling the segment out after you've made a cut alongside one of the membranes. Continue to work around the grapefruit until you've cut out or removed all of the segments, without their connective membranes.
Peel and slice the avocados. Arrange slices of avocados and grapefruit segments on a plate on a bed of a few lettuce leaves.
Spoon dressing over the salad.