Next time you are peeling a carrot or a knob of ginger, don’t throw out those peels! They can be transformed into a slightly spicy, sweet soda base. You can even make this syrup with frozen peels, so you can collect them over time in the freezer.
For the carrot ginger syrup: Stir together the carrot skins, sugar, ginger skins and 1 1/2 cups water in a medium saucepan and bring to a boil over medium heat, about 8 minutes. Reduce the heat to low and simmer, stirring occasionally, until bright orange and slightly syrupy, 20 minutes. Remove from the heat and set aside to infuse for 15 minutes. Strain into a heat-resistant container and discard the solids. Cool, transfer to an airtight container and refrigerate until ready to use and for up to 1 week.
For the carrot ginger soda: Fill 4 tall glasses halfway with ice. Add 1/4 cup syrup and 1 cup seltzer to each glass, stir and serve.