Place the kale into a salad bowl. Toss with the carrot, orange juice, lemon juice ,and salt, and using your hands, rub the acid into the kale. Let the kale sit a few minutes.
Prepare a large bowl of ice water and a saucepan with boiling water. Place the thinly sliced onion into the boiling water for 15 to 30 seconds, and then shock them in the cold water, stopping the cooking immediately. Drain the water and blot the onions with a paper towel.
Add the onion, bacon, olive oil, salt and pepper and toss well. Add the mayonnaise and mix the slaw well. Refrigerate until ready to serve. Can be made several hours in advance.