A member of the chicory family, frisee is a fragile lettuce with slightly bitter notes. While it can add an interesting dimension to your salad, don't worry if you don't have it to hand or you can't find it at the store. Several other lettuces or salad greens make reasonable substitutes for frisee lettuce.
Eat Some Escarole
Like frisee lettuce, escarole is a member of the chicory family. It's probably its closest relative and makes the best substitute. Not only does escarole look quite like frisee lettuce with its curly leaves and fresh green color, but it also has a comparable mildly bitter flavor and a similar crisp, yet delicate mouth feel. Unlike frisee, you can cut it with a knife, but otherwise use it in the same way as you would use frisee in your recipe.
Enjoy Some Endive
Endive -- also known as Belgian endive -- is another member of the chicory family that works well as a substitute for frisee lettuce. It has similar bitter and slightly peppery notes so will taste much the same as frisee in a salad. However, this crunchy green has quite a different texture. It will also give your final dish a different appearance, as it's mostly white with some pale green.
Revel in Radicchio
With its large, striking red leaves, radicchio might not look much like delicate frisee lettuce. However, as part of the chicory family, the two are related. Its bold coloring will make your salad stand out, but it has a slightly bitter taste similar to frisee. While it has more of a fresh, crisp crunch to it, your final dish will be much the same if you replace the frisee lettuce with radicchio.
Opt for Additional Alternatives
If you want to focus on the complex, bitter punch that frisee lettuce gives you, try using dandelion greens as a substitute. Only use young leaves in a salad, as older leaves are too bitter unless cooked. If you like the peppery taste of frisee, give arugula a chance. Mustard greens are both slightly bitter and sharply peppery, so they make a good middle ground. Fennel is another possible substitute, but it has a rich anise flavor that you don't find in frisee.