SHED's Blood Orange Champagne Vinegar Shrub

Juice oranges until you get 1 cup juice. Cover and refrigerate the juice. Using a muddling stick or a wooden spoon, muddle (gently grind and smash) the orange peels with sugar in a nonreactive mixing bowl (see Tip) until the peels start to break down. Let stand, uncovered, at room temperature for at least 12 hours and up to 1 day.

Add the reserved juice to the bowl with the peels and sugar; stir until the sugar is fully dissolved. Strain through a fine sieve. (Discard peels.) Combine the strained juice and vinegar in a bottle or jar. Cover and refrigerate for at least 1 week (and up to 3 weeks) to let the flavors marry. As the mixture rests, the flavors will coalesce. The vinegar mellows while the citrus starts to come to the front.

To make the final drink, pour 1 ounce (or up to 2 ounces) of the vinegar mixture into a tall glass over ice. Top with about 10 ounces sparkling water (or seltzer). Garnish with a sprig of fresh rosemary.