He explained that they put a little milk in it to keep it from turning black. The chefs apparently didn't know that leaving the avocado pits in it will keep it from turning black. I've seen guacamole with pits sit outdoors for hours on a warm summer afternoon without turning black, so I know this works. And it doesn't endanger people with dairy allergy! Or lactose intolerance.
I'm sure dairy is the last thing most people expect in guacamole. It usually contains avocados, onions, peppers, and salt. Some add tomatoes or other vegetables. But milk? That's crazy! Since people don't expect milk in guacamole they might not refrigerate it, which could cause food poisoning.
This is discouraging because I had thought it was one of the few foods I could count on to be free of my allergens of soy, dairy, egg and sugar.
A few weeks later I was at another restaurant and the guacamole they brought me was smooth and flecked with green herbs. It turned out to be made of avocados and sour cream. A better name for this would be avocado spread or dip.
Let's try to stop this craziness from spreading. If you work in a restaurant or food preparation, please don't contaminate the guacamole with dairy! If it contains avocados but isn't guacamole, please don't call it that. :p