Prepare your wine glasses or champagne flutes. Use a microplane to remove the zest from one tangerine. Mix the zest of 1 tangerine with 2 tablespoons of sugar. Wet the rim of the glass with a slice of tangerine and dip in the glass in the sugar to coat the rim.
Using a strainer, pour the mixture into 2 champagne or wine glasses, filling the glasses two third full.
Top the glass off with prosecco or champagne.