Place broth and spinach in a frying pan. Cook over medium heat. Slowly stir spinach around pan until begins to wilt.Add vinegar and oil and stir.
Place all spinach in center of pan and add egg gently to the topc of spinach. Put a lid over the pan, turn to low heat and cook until egg sets (about 4-5 minutes).
Carefully scoop spinach and egg onto your plate and enjoy!