Ranchero dressing is a type of Mexican-style dressing made from a combination of mayonnaise, sour cream, and salsa. It is often used as a topping for tacos, burritos, and other Mexican dishes. The term 'ranchero' refers to the traditional Mexican style of dress, which includes serapes, or brightly colored blankets with fringed edges. Serapes are often worn draped over the shoulders or around the waist.