Curly parsley and flat leaf parsley are two different varieties of the same herb, Petroselinum crispum. Both types of parsley contain vitamins A, C, and K, as well as iron and other minerals. They are used in similar ways, but have differences in both appearance and flavor.
Curly parsley has curly leaves that are bright green, and it has a mild slightly peppery flavor. Flat leaf parsley, also known as Italian parsley, has dark green flat, serrated leaves, and a slightly bitter taste with a hint of sweetness.
Flat leaf parsley is often used in cooking, as its flavor contributes well to recipes like soups and stews, salads, and salsas. French persillade comes from the French word for parsley, persil, and is a combination of parsley and garlic that is used to season a wide variety of dishes.
Curly parsley, milder in taste than flat leaf parsley, is often frowned upon as an ingredient, largely because of its ubiquitous use as a garnish in the 1950s, where a sprig on a plate was intended to be purely decorative. But curly parsley does has flavor and its ruffled leaves have a pleasant crispy texture and distinctive color ideal for mincing to add to marinades, vinaigrettes, and foods that are bland in color.
Choose Italian (flat leaf) parsley for stocks, soups, bouquet garni, and braised foods. If using primarily for flavor, use leaves and stems, bearing in mind that they will wilt and turn grayish-brown, and therefore should be removed at the end of cooking. For bright flecks of color, add chopped or minced parsley (of either type) toward the end of cooking.
When selecting parsley, choose fresh, bright green leaves with no signs of wilting or discoloration. Rinse it well in a bowl of water, changing the water as needed to remove any soil or sand. Wrap the wet parsley in a paper towel, place it in a compostable or other eco-friendly bag, and refrigerate.
Parsley can also be chopped and frozen, preserved in oil or added to compound butter, but none of these methods will preserve the color, texture, or flavor of fresh parsley.