With a sharp knife, cut peel and outer membrane from grapefruit. To release fruit segments, hold grapefruit over a bowl and cut between membrane and fruit. Squeeze membrane juice into bowl. Discard peel and membrane.
Cut avocado in half, pry out and discard pit, then pull skin from avocado and discard. Moisten avocado halves with a little of the grapefruit juice and set aside.
Trim discolored stem ends from endive. Finely sliver endive vertically and lay slivers on 4 salad plates.
Cut avocado halves vertically into slices. Arrange equal portions of avocado and grapefruit segments with endive on each plate.
To grapefruit juice, add lime juice and honey. Whisk to blend. Drizzle salads with this dressing, then sprinkle with pistachios and add salt to taste.