Does everything have to be authentic? This filling would also make a nice panini or flatbread sandwich.
- Heat oil in a medium skilled over medium heat. Add onions and cook 3 to 4 minutes, stirring occasionally, until softened. Sprinkle in sugar and cook another 10 minutes until onions are browned; do not burn. Stir in the spinach and remove skillet from heat.
- Heat another skilled over medium high heat. Add one tortilla to dry skillet and cook 15 seconds. Sprinkle half the tortilla with 1/2 cup cheese, place 1/4 of the spinach filling on top, add 1/4 of the pepper strips. Fold empty half of the tortilla over the filling and press down with the spatula about 10 seconds.
- Slide quesadilla onto serving plate. Repeat with remaining ingredients.