Crabmeat, cucumber and grapefruit salad

Makes 2 servings

3/4  large pink grapefruit
1 ripe avocado 1 large, stoned and cut into chunks
 1/2 medium cucumber, seeded and sliced
2 handfuls  lettuce
5 oz white crab-meat

Dressing:
4 tablespoons olive oil
1/4 pink grapefruit, juiced
2 teaspoons grainy mustard
Salt and pepper to taste

Divide the lambs lettuce between plates. Add the avocado, cucumber and grapefruit, then the crabmeat. Spoon the dressing over to serve.