A riff on a White Negroni, originally incorporating a generous dosing of two types of rhubarb bitters. (Also works well with 15ml / 1oz Fee Brothers Rhubarb...
I halved the measure of Suze (Gentian) as this can easily dominate other flavours.... Used Plymouth Gin. All in all, a cocktail with a unique flavour, the dry Gentian tempered by the fruity Rhubarb Bitters - 15 ml being the most of any bitters I have deployed in a cocktail. On a second mux, I topped with sparkling mineral water. Refreshing and a bit different. Oh, it has a kick, too!