"Майонез, будь ласка."
There are so many various types of mayonnaise in Ukrainian supermarkets. It's rather incredible.
Versions with horseradish (хрін) are particularly popular.
Now you're making me doubt my memory. Perhaps it was ketchup with horseradish. But then again, I remember horseradish appearing everywhere.
Martha Stewart's "Ukrainian Mayonnaise" recipe includes horseradish, so maybe I'm not crazy. http://www.marthastewart.com/355907/ukrainian-mayonnaise