Gem lettuce is a miniature variety of romaine lettuce that has been available for many years, but became much more popular in the late 20st century. This small lettuce variety has a oblong head of loosely-furled green leaves and is eaten in salads, wraps, and sandwiches. A red variety with greenish outer leaves and a burgundy heart is also available. This lettuce should be stored in the crisper drawer of the refrigerator inside a plastic bag or lettuce keeper for up to one week.
This miniature variety of lettuce looks similar to its larger relative, romaine lettuce, but has a slightly sweet to nutty flavor and a thinner, crisper stalk. Also called Little Gem, it is frequently served in higher-end restaurants as part of the salad course, and offers an interesting alternative to conventional iceberg lettuces. Gem lettuce is an old variety, originally native to France and Spain, and includes some heirloom types of lettuce.
The lettuce itself produces a compact but loose head about 5 inches (13 cm) long by 3 inches (8 cm) wide, with crisp green leaves that have a crinkled or ruffled edge. Many cooks halve or quarter this tiny lettuce for single-serving salads, and then top it with cheese, dressing, or meats. Gem lettuce also makes an attractive setting for fish and meat dishes and provides a convenient leaf size and texture for sandwiches and lettuce wraps. Gem also works well when cooking with lettuce; it can be brushed with vinaigrette and grilled briefly or blanched and braised whole for a side dish.
While most gem lettuce is green, there is a red gem variety that adds a little extra interest to the plate. This lettuce's leaves vary from brownish to burgundy or purple, usually darkening toward the heart. The taste of red gem lettuce is similar to that of the green variety, and you can substitute it for Little Gem or Sweet Gem varieties in any recipe.
Like other leafy greens, gem lettuce is a relatively delicate vegetable and won't keep long. Store it in the vegetable or crisper compartment of a refrigerator, either in a loose plastic bag or lettuce keeper, for up to seven days. Ventilated containers will allow the lettuce to stay crisp for longer. You may be able to keep gem lettuce for longer than a week, but it will tend to lose its crispness and may develop discolored spots. Lettuce that is no longer fresh enough for salads may still work on the grill, in braised dishes, or as lettuce soup.