Rinse the untreated lemon and cut the peel into strips.
Place the cherries, lemon peel strips, and brown rock sugar into a large glass jar with a tightly-fitting lid. Pour in the vodka until full. Seal tightly.
Store in a warm place (preferably on a windowsill) for 2 months to infuse.
Shake the jar every few days so the sugar dissolves completely.
Pour the mixture through a fine sieve or cheesecloth into a clean container, gently pressing the cherries to extract the liquid.
Transfer to clean bottles and seal. Let rest for 2 more weeks before serving.