1. Combine all ingredients except kale in a small saucepan. Heat until slightly warm and combined. Transfer mixture to a bowl and stir in the kale leaves. Cover in plastic wrap and refrigerate, allowing kale to soak for at least 4 hours.
2. Preheat a grill or a cast-iron grill pan over high heat. Remove the kale from the refrigerator and stir to make sure the leaves are well covered in marinade. Using metal tongs, place the kale on the grill in a single layer. Cook for 45 to 60 seconds, or until the leaves are sizzling, then turn over and grill the other side for another 45 to 60 seconds, or until the leaves have visibly softened. Serve immediately.