Lemon Drop Martini    1 1/2 ounces vodka (use a good-quality vodka)  1/2 ounce orange liqueur (Triple Sec, Grand Marnier, Cointreau, etc.)  1 teaspoon superfine sugar or to taste*  3/4 ounce freshly-squeezed lemon juice  Ice cubes  Superfine sugar for dipping  Twisted peel of lemon