Freshly squeezed Meyer-lemon juice brightens the mustard vinaigrette in this simple salad and tempers the bite of the watercress, arugula, and frisee. Try pairing it with Pork Wellington with Prosciutto and Spinach-Mushroom Stuffing.
In a large bowl, whisk together lemon juice, mustard, and sugar. Slowly add oil in a thin stream, whisking constantly; generously season with salt and pepper. Add greens; toss until leaves are evenly coated in dressing. Serve.
You can prep this salad up to eight hours ahead. Place clean, dry greens in a bowl on top of the dressing, cover, and refrigerate. Remove 20 minutes before serving and toss.