If making the lemon-lime syrup, place the citrus peels in a small saucepan, and add the sugar and salt. Use a muddler or the end of a rolling pin to break down the mixture, working the sugar mixture into the peels until they start to express their oils. Add the lemon juice and stir to combine. Heat over low, stirring frequently, just until the sugar dissolves. Immediately remove the pan from the heat and set aside to steep for 1 to 2 hours. Strain through a fine-mesh sieve, pressing on the solids. (You should have about 1 cup syrup. The syrup can be stored, in an airtight container in the refrigerator, for up to 3 weeks.)

In an ice-filled cocktail shaker, combine the wine, vermouth and syrup, if using. Cover and shake until cold, then strain into an ice-filled highball or wine glass. Top with soda (or soda water), and mix gently to combine. Garnish with the lemon wheel and serve.