In a skillet over medium high heat, caramelize the onions in 1 teaspoon butter. Stir frequently until the onions are soft and caramel colored (about 15 minutes).
2
In a small bowl, combine the yogurt, lemon juice and olive oil.
3
Add salt and pepper to taste.
4
Spread mixture over tortilla(s) and place cheese on top.
5
Next, add the warm onions, apples and another portion of cheese.