Fresh Spinach with Bacon and Vinegar

My husband's mother used to make this and I had completely forgotten about it until he suggested I make it.

10 ounces of fresh, cleaned spinach, baby or regular

4 slices thick bacon

1/2 onion, chopped

2 T. white vinegar (or more to taste)

fresh salt and pepper

1. Cook bacon and onion together in a large skillet until browned.
2. When cooked, add all the spinach.  Toss until wilted.
3. Add the vinegar, salt and pepper and serve warm.