Heat a cooking spray coated frying pan over medium heat. Lay 4 onion slices in the pan and top with 1/2 teaspoon sugar. Cook 4 minutes per side or until lightly browed. Wipe frying pan clean and cook the rest of the onions with the sugar.
Mix greens, apple, and cheese in a serving bowl.
Whisk together water, vinegar, oil, salt, and pepper. Spoon mixture over top of greens and top with onion slices.