"Gem lettuce" refers to a type of lettuce that has small, compact heads and crisp leaves. It is often used in salads or as a topping for sandwiches. Full definition
Classic British Coronation chicken gets a makeover, served in Little Gem lettuce leaves with peanut and coconut sauce (bbcgoodfood.com)
The Breakfast Salad, Creole Cauliflower, Sticky Carrot Bites and Baby Gem Lettuce Wraps with Homemade Sweet Chilli Sauce. (coconutandberries.com)
Monday's lunch was a Thai soya bean and egg salad made with shredded carrots and beansprouts, piled onto sweet gem lettuce leaves seasoned with a dash of tamari and lime. (itcomesnaturallyblog.wordpress.com)