Apple, Fennel and Blue Cheese Salad with Toasted Walnuts

Serves 4

1 Fuji or Red Delicious apple
2 Tbsp fresh lemon juice
1 1/2 cup thinly sliced fennel bulb
2 small heads of Boston lettuce
1/2 cup walnuts, toasted lightly and chopped
3 oz blue cheese (preferably Maytag or Roquefort), crumbled about 1/3 cup
2 tsp Dijon mustard
4 Tbsp sour cream
1/2 cup olive oil

In bowl, toss sliced apple with 1 Tbsp of lemon juice, add the sliced fennel, the lettuce and the toasted walnuts and toss until combined. In blender, blend together blue cheese, vinegar, remaining 1 Tbsp lemon juice, mustard, sour cream, oil, 2 Tbsp water and salt and pepper to taste. Pour dressing over apple mixture and toss the salad until it is combined well.