Think of this drink as a Martini-plus: It’s “very simple and straightforward, but at the same time there’s more than meets the eye,” says Berg, who is noted for using boundary-pushing techniques that trick the palate. (A note: “Simple” is definitely in the eye of the beholder. The core ingredient list is indeed streamlined, but you need at least four days, and maybe more, to get those ingredients prepared.)
Berg is partial to the butter from Fannremsgården (Fannrem Farm), which she considers the “real star” of the drink. “It is made in a very traditional way, using sour cream as the starting point. This gives it richness but also lots of acidity and depth of flavor.” It doesn’t hurt that Berg’s own calf—Ramos, as in the dairy-based fizz—lives at Fannremsgården. But if Fannremsgården is not available, and you have no such allegiances, any good butter will do.