In a small pot, bring water, vinegar, and salt to a simmer over medium heat. Have two clean pint jars ready. In one jar, place fennel seeds, peppercorns, and lemon peels. In the other pint jar, place dried rosemary, coriander, and orange peels. Then stack up the kohlrabi slices in both jars until they almost reach the top. Once water-vinegar mixture has simmered, pour into both jars to fully cover kohlrabi, seal tightly with lids, and allow to cool to room temperature before putting in the refrigerator. Let sit for 24 hours before eating.