There are many different possible ways to serve romaine lettuce. It can be eaten raw as a salad or steamed as a vegetable dish. The braised leaves also make a delicious warm side dish.
From Wikipedia: “Romaine or cos lettuce is a variety of lettuce (Lactuca sativa L. var. longifolia) that grows in a tall head of sturdy leaves with firm ribs down their centers. Unlike most lettuces, it is tolerant of heat.”
“In English, the most common name in North America is "romaine", while elsewhere it is known as "cos lettuce". Many dictionaries trace the word cos to the name of the Greek island of Cos, from which the lettuce was presumably introduced. Other authorities trace cos to the Arabic word for lettuce, khus خس [xus].
It apparently reached the West via Rome, as in Italian it is called lattuga romana and in French laitue romaine, both meaning 'Roman lettuce', hence the name 'romaine', the common term in North American English.”
“In North American supermarkets, romaine is very widely available year-round. The thick ribs, especially on the older outer leaves, should have a milky fluid which gives the romaine the typically fine-bitter herb taste. Romaine is a common salad green, and is the usual lettuce used in Caesar salad. Romaine lettuce is commonly used in Middle Eastern cuisine. Romaine, like other lettuces, may also be cooked, for example braised or made into soup.”
“Romaine lettuce may be used in the Passover Seder as a type of bitter herb, to symbolise the bitterness inflicted by the Egyptians while the Israelites were slaves in Egypt.”
“As with other dark leafy greens, the antioxidants contained within romaine lettuce are believed to help prevent cancer.”
“The day of 22 Germinal in the French Republican Calendar was dedicated to this lettuce, as "Romaine".”