In a small bowl, whisk together vinegar, sugar, and salt. Place cherries in one small bowl or jar and kohlrabi in another. Pour half the vinegar over cherries and the other half over the kohlrabi, stirring to coat. Set aside while you make the rest of the salad, about 10-15 minutes.
For the salad:
In a small bowl, whisk together olive oil, salt, lemon juice, and honey. Pour over kale leaves and use your hands to massage kale until it breaks down and softens, about 5-6 minutes.
Toss kale with red onion, cherries, and kohlrabi. Top with Parmesan cheese and freshly ground black pepper.