And now a completely useless Salad Day fact: The word salad is originated from the Latin Herba Salata, meaning salty herbs. The Romans made salad dressings from salt brines and put them on various raw vegetables. However the modern salad has only existed since the 16th century, and modern salad dressings only date back to the 19th century.
Does 'modern dressings' mean stuff based on mayonnaise? That might be right. But oil and vinegar goes way back. The 1699 Acetaria is a long book on vegetarianism, with a discourse on salads ('sallets'), and basic dressing ingredients of olive oil, wine vinegar, salt, mustard, pepper. One dressing, '[79]', says 3 parts olive oil, 1 part vinegar or other acid, horseradish, mustard seed, and two egg yolks (boiled, so probably not an impromptu mayonnaise.)
Going further back, Columella, a Roman from the first century AD, had a salad recipe with oil, vinegar, and salted cheese, over lettuce and arugula/rocket. Though he seems to crush the leaves in a mortar with all the other ingredients, so I guess you get a weird salad paste.
Apicius apparently also had oil and vinegar dressings. With stock or brine, presumably for the salt.
