Chop the kale, red cabbage, carrot, and apple as noted above. Place them in a large bowl.
In a medium bowl, whisk together the olive oil, apple cider vinegar, maple syrup, Dijon mustard, and kosher salt. Pour the dressing onto the vegetables and toss to combine.
If desired, toast the almonds and toss them into the slaw just before serving. Stores up to 4 days refrigerated. (For crunchy almonds, store them in a separate container at room temperature and add directly before serving).