Prepare the jars. Divide the sliced radish, shallots, and chopped cilantro between two pint jars.
1 lb radish, 1 medium shallot, ¼ cup chopped fresh cilantro
Make the brine. In a saucepan, combine the vinegar, water, sugar, salt, and cumin seeds. Set over medium heat, stir, and bring to a boil. Once the sugar and salt have dissolved, remove the pan from the heat.
1 cup distilled white vinegar (5%), 1 cup water, 2 tsp granulated sugar, 4 tsp kosher salt, ½ tsp cumin seeds
Add to the jars. Pour the hot brine mixture over the top of the radishes, dividing the liquid between the jars. Place a lid on top of each jar and store in the refrigerator for at least 1 hour before consuming.