For the salad:
8-12 oz. baby spinach leaves, rinsed and dried
4 oz. button mushrooms, thinly sliced
3-4 hard boiled eggs, peeled and sliced
¼ medium red onion, thinly sliced
For the dressing:
6 slices thick bacon (about 6 oz.), finely diced
¼ cup red wine vinegar
1 tsp. honey or sugar
1 tsp. Dijon mustard
Salt and pepper, to taste
In a large salad bowl, combine the spinach, mushroom slices, hard boiled eggs, and onion. Toss gently to mix.
Heat a large skillet over medium-high heat. Add the bacon to the pan and cook, stirring occasionally, until the pieces are just crisp. Remove the bacon bits with a slotted spoon or skimmer to a paper towel-lined plate. Pour the bacon fat into a bowl or liquid measuring cup. Remove the pan from the heat and return 4 tablespoons of the bacon fat to the pan. Slowly drizzle in the vinegar at the edge of the pan and whisk to blend. Whisk in the honey and Dijon. Season with salt and pepper to taste. Drizzle some of the dressing over the salad and toss gently to coat. Add additional dressing as needed, to taste. Serve warm.