In a small bowl, mix mustard, lemon juice, shallots, salt, and pepper. Let stand at least 10 minutes.
Line a large, shallow serving bowl with the radicchio leaves.
Whisk oil into mustard mixture. In a bowl, pour dressing over frisée; mix gently, then mound on radicchio. Sprinkle with parsley.
Servings 0
* Percent Daily Values are based on a 2,000 calorie diet. Your daily value may be higher or lower depending on your calorie needs.