Avocado and Grapefruit Salad

4 pink grapefruit
4 avacoados
1/4 cup lime juice
1 tbsp dijon mustard
salt and pepper
1/3 cup oilive oil
8 whole boston lettuce leaves
1 tbsp chopped chives

Peel a grapefruit, cutting away as much pith as possible. Over a bowl, cut flesh away from membranes and allow fruit to fall into bowl. Repeat with remaining grapefruit.
Halve avocados lengthwise and remove pits. Scoop out flesh with a spoon. With a stainless-steel knife, cut avocado lengthwise into 1/4 inch thick slices. Sprinkle with 2 tbsp lime juice to keep from turning brown.
Whisk 2 tbsp lime juice with mustard, salt and pepper. Gradually whisk in oil.
Place lettuce leaves flat on a platter. Arrange grapefruit segments and avocado on top. Drizzle salad with dressing, sprinkle with chives and serve.