Some restaurants make their own Ranch dressing. When I was a salad bar attendant (yes, that was my title) for a summer as a teenager, I was schooled in making Ranch dressing "from scratch." The process is sort of gruesome (combining one part mayonnaise, one part buttermilk, and spices; we used to make it a gallon at a time so 1/2 gallon of each = bleh) but it does come out tasting pretty good and is less expensive than ordering a gallon of Ranch dressing from a supplier.