How to Make It
Fill a chilled collins glass with ice. Squeeze the grapefruit and orange wedges into the glass, then drop them in. Add the Sanbittèr, Terma Amargo Serrano and bitters and stir well. Garnish with the thyme sprig and lemon twist.
Sanbittèr soda is sold at Italian markets. Terma Amargo Serrano is available at gauchogourmet.com and at Latin markets.