In a small saucepan over medium-high heat, fry bacon until crispy. Transfer to a plate lined with paper towels.
Keeping the saucepan hot, stir in vinegar and sugar until the sugar is dissolved. Keep warm over the lowest possible heat.
Meanwhile, in a serving bowl, combine greens and reserved bacon pieces. Immediately before serving, pour the hot dressing over the top of the salad and toss to combine. Season to taste with salt and pepper.