Step 1

Put the chopped bacon in a heavy bottomed pot or large skillet.

Step 2

Cook over medium heat until it’s nearly browned and the fat is rendered.

Step 3

If there's excess fat, pour out all but about 3 tablespoons bacon drippings. Add the chopped onions to the pan.

Step 4

Cook, stirring frequently, until the onions are browned and caramelized, about 15 minutes.

Step 5

Reduce heat to medium-low, add the balsamic vinegar, brown sugar, and mustard, and cook, stirring often, until the mixture is thick and jammy, about 30 to 40 minutes.

Step 6

Remove from the heat, cool for 15 minutes, and season to taste with salt and pepper. Transfer to a serving dish and enjoy! (If making ahead, cool to room temperature and transfer to a tightly sealing container or glass jar and refrigerate.)