How to Make It
In a salad bowl, whisk together the oil, vinegar, mustard, sugar, 3/4 teaspoon salt, and 1/2 teaspoon pepper.
Remove the kale from the stems and pulse the leaves in batches in a food processor until finely chopped.
Toss the kale, apple, onion, and pecans with the dressing. Season with salt and pepper to taste and serve.