It is just an emulsification—egg yolks and butter Lower by way of with vinegar flavored with tarragon and shallots, which has a bite of black pepper. Think of it being a free mayonnaise, demanding only a lot of whisking as well as a careful hand with the heat to learn. https://gunnerqwydi.isblog.net/the-fact-about-sauce-apple-fritter-hybrid-that-no-one-is-suggesting-43804002