Frisée and radicchio are both assertive, slightly bitter greens that add color and texture to any salad. Match them with mellower-flavored greens, such as red leaf lettuce, baby spinach or even Boston lettuce.
Combine orange juice, lemon juice, oil, shallot, mustard, salt and pepper in a jar with a tight-fitting lid. Close the jar and shake until well combined.
Place greens and onion in a large salad bowl; toss with 1/3 cup of the dressing.
Make Ahead Tip: Cover and refrigerate the dressing (Step 1) for up to 3 days. Bring to room temperature and shake before using.
1 vegetable, 1 fat