Remove stems and veins from spinach (either discard or save for adding to your homemade soups). Tear spinach into bite-sized pieces; place spinach in a large bowl.
In a small frying pan over medium heat, fry bacon approximately 5 minutes or until crisp; transfer the cooked bacon with a slotted spoon to paper towel-lined plate; set aside. Leaving approximately 2 tablespoons of bacon fat in the pan.
When bacon has cooled, crumble it into small pieces and then set aside.
Return frying pan to medium heat; add olive oil, onion, salt, pepper, and sugar. Cook 2 to 3 minutes, stirring occasionally, until onion is slightly softened. Add balsamic vinegar; swirl to incorporate. Remove from heat.
Pour warm dressing over prepared spinach and toss gently to wilt (when properly wilted, the leaf edges soften slightly, but the spinach retains some crunch). To avoid overly wilted spinach, we used a mere 1/4 cup of dressing for 6 cups of greens in our spinach salad recipe.
Sprinkle the crumbled bacon and blue cheese over the top of the spinach and serve immediately.
Makes 4 servings.
* I like to use the fresh baby spinach leaves.
Wilted Spinach Salad with Bacon and Balsamic Vinaigrette Recipe: https://whatscookingamerica.net/Salad/SpinachBalsamic.htm