Decide if you want to use your shaker or not. It's nice for muddling mint and for getting the liqueur nice and cold if it's not already chilled—shake-shake-shake with ice then strain into an ice-filled glass (fresh ice).  

Alternatively, muddle mint directly in glass. Or save the mint for garnish.

Start with a shot of St-Germain (approx. 1½ ounces), then top with 2 shots green tea (about 2 ounces, which is a heaping shot; ¼ cup; 4 tablespoons), and 2 shots Prosecco. Stir, swizzle, what have you, and add club soda if you want more bubbles. Garnish with a circle of lime and sprig of mint or a lemon wheel. Cheers!