Step 1

Place the butter or olive oil in a large skillet and heat over medium heat, until the butter is melted (if using).

Step 2

Add the shallots, onions, or garlic and sauté for 1 to 2 minutes until just barely golden but not browned. Season with salt and pepper.

Step 3

Add the kale, in batches if necessary, and the liquid, and stir until it is wilted to how you like it and the liquid has evaporated. Add the vinegar and red pepper flakes, if using, and toss to combine well. Check and adjust seasonings as needed. Turn into a serving dish.