Found in specialty produce markets and many supermarkets, mesclun (also called salad mix and gourmet salad mix) is simply a potpourri of young, small salad greens. The mix varies depending on the source, but among those greens commonly included are arugula, dandelion, frisée, mizuma, oak leaf, mâche, radicchio and sorrel. Choose mesclun with crisp leaves and no sign of wilting. Refrigerate in a plastic bag for up to 5 days. Wash and blot dry just before using.