Preheat oven to 350 degrees.
In a large zipper-topped plastic bag, combine salt, pepper, cayenne pepper and half of the garlic; shake the bag to combine ingredients. Add beef cubes and shake well to coat.
Thread beef cubes onto skewers and place them on a lightly oiled metal rack or trivet in a 9- x 13-inch baking dish. Cover with aluminum foil wrap and bake for 45 minutes to 1 hour or until desired level of doneness is reached.
Meanwhile, in a small saucepan over medium heat, combine onion, Dijon mustard and honey; cook for 10 minutes, stirring often, until onion is soft.
Serve roasted beef skewers over equal portions of chopped kale and top with Honey Mustard Onion glaze.