1. Cook the bacon in a large skillet over medium-high heat, turning occasionally, until crisp. Transfer with tongs or a slotted spatula to a paper towel–lined plate to drain. Reserve the drippings in the skillet.

2. For the salad dressing, add the vinegar, water, sugar, salt and pepper to the drippings. Cook, stirring, until heated through.

3. For the salad, combine the spinach, oranges, and onion in a salad bowl and toss to mix. Pour the dressing over the salad and toss to mix well. Crumble the bacon over the top and serve.

Variation
For a more substantial  salad, garnish with sliced hard-cooked eggs.