In a large bowl, combine the olive oil, vinegar, mustard, honey, ginger, and 1/8 teaspoon of salt and several grinds of black pepper. Stir well.
Remove the tough stems from the kale leaves and chop them into small pieces, so that the salad is easy to eat. Add the kale to the bowl of dressing, and use your hands to "massage" the dressing into the kale. The kale should soften and shrink as you do this.
Stir in the carrots and onions, adjust any seasoning to taste, then serve right away with sliced avocado on top. If you don't plan to serve this right away, I would wait to slice the avocado so that it doesn't brown.
I like this salad best when eaten right away, but it can be stored in an airtight container in the fridge for up to 48 hours without getting too soggy.
If you don't have red onion on hand, green onions work really well in this, too! I also like to add dried cranberries to this salad when serving it for a party.