Place the cucumbers, radishes, beets and kosher salt in a colander and toss to combine. Allow to “sweat” for 30 minutes. Rinse with cold water, drain well and set aside.
Place the vinegar, water and sugar in a large bowl and whisk until sugar has dissolved.
Add the mustard seeds, peppercorns, cumin seeds and vegetables. Stir to combine.
Let sit 1 – 3 hours at room temperature before serving.