Cucumber Sekanjabin Sharbat

Bring 1 cup sugar, ½ tsp. Diamond Crystal or ¼ tsp. Morton kosher salt, and ⅔ cup water to a boil in a small saucepan, stirring to dissolve sugar. Reduce heat and simmer, stirring occasionally, until syrup is slightly thickened, about 3 minutes. Remove from heat and add 2 mint sprigs, then stir in 3 Tbsp. apple cider vinegar to combine. Let syrup sit at least 15 minutes and, preferably, up to 2 hours. Discard mint.

Transfer syrup to a pitcher. Pick leaves from remaining mint sprigs and finely chop. Add water to whey from labneh to make 2 cups. Add 6 Persian cucumbers, grated on the small holes of a box grater, mint, and whey to pitcher; stir to combine. Add 3 cups ice and stir until sharbat is very cold. Taste and add more water or vinegar if needed.

Pour sharbat into tall glasses and serve with spoons for scooping up cucumber bits. Do ahead: Syrup can be made 3 days ahead. Transfer to an airtight container; cover and chill.