I, too, was confused by the specification of both lemon and orange flamed zest twists, so I used one of each. According to Death & Co.'s "Modern Classic Cocktails," which is probably as close to Phil Ward's original recipe as we're gonna get, the official garnish is a flamed orange "coin," as shown in Difford's photos. I've watched video of Dale DeGroff igniting flaming orange coins and it looks like you get just one good flaming squeeze per coin (don't burn your fingers). I don't do coins and can attempt several pyrotechnic squeezes out of a good-size zest strip. A great Negroni variation with more body than the standard recipe. And no, I haven't read the book.