Place shredded cabbage in a large colander set over a sink or large bowl. Sprinkle with Kosher salt, then toss to thoroughly coat. Allow cabbage to drain.
In a large mixing bowl, whisk together mayo, sour cream, and the juice of limes.
Transfer the drained cabbage to the large mixing bowl with the dressing, then add thinly sliced red onion, scallions, and fresh cilantro. Toss well, then refrigerate until needed.
Taste, adjust seasoning, then serve!