Prepare shred the cabbage and radicchio. Slice and peel the apples.
Tear the arugula into small pieces. Discard the outer leaves of the fennel, thinly slice the remainder.
Arrange all of the ingredients in a salad bowl. Put the capers, vinegar, mustard, egg yolk, parsley, oil, and salt an pepper to taste. Blend ingredients with a food processor or in a blender and blend until creamy. Pour into salad and toss. Serve immediately.Makes 6 Source: