Combine the zest of 2 lemons (in wide strips), 1 cup water, 1/2 cup sugar and 1 cinnamon stick in a pot over medium heat; bring to a simmer and cook until the zest is slightly translucent, 6 to 8 minutes. Strain; reserve the lemon zest and syrup and discard the cinnamon stick. Put the lemon zest in a food processor; add 1 1/2 pounds frozen cherries (thawed and drained) and a pinch of salt. Pulse, adding 1/4 to 1/2 cup of the sugar syrup to loosen. Add 1 to 2 teaspoons lemon juice.