Toss the cabbage, carrot, and salt together in a colander set over a plate.
Let stand until the cabbage wilts, at least 1 hour or up to 4 hours.
Rinse the cabbage and carrot under cold running water (or in a large bowl of ice water if serving immediately).
Press, but do not squeeze, to drain; pat dry with paper towels. Place into the refrigerator until ready to serve.
When ready to serve, combine the mayonnaise, vinegar, and celery seed together in a large bow; whisk until well combined.
Add the cabbage, carrot, minced onion, fresh cilantro, and season with sea salt and freshly cracked pepper, to taste; toss until evenly coated.
Serve chilled or at room temperature. Store leftovers in an airtight container for up to 2 days. Enjoy.