A popular beverege that Romans drank for 1000 years and noone bothered to mention the recipe because heck what's the point, everyone knew it.
So my first attempt was to mix white refined winegar with room-temperature water. Resulting taste: disgusting.
Second attempt: aceto balsamico di modena and cold, sparkling mineral water (about 1 part vinegar and 10 parts water). Resulting taste: quite good.