A Caesar salad was a type of Earth salad.
In the late 2250s, Caesar salad was one of the many food items vomited out by food synthesizers when Me Hani Ika Hali Ka Po and Sylvia Tilly were in the mess hall aboard the USS Discovery. (ST: "Runaway")
In 2374, Kira Nerys and Odo both enjoyed a Caesar salad prior to dining on Chateaubriand in Quark's holosuites. The meal was prepared by Vic Fontaine. (DS9: "His Way")
The Star Trek Encyclopedia (4th ed., vol. 1, p. 112) described this salad as a "vegetable dish made with fresh Romaine lettuce, lemon juice, chicken egg, and a pungent dressing made from a small, cured Earth fish called an anchovy."