1. Preheat the oven to 350 degrees F.In a small bowl, mix together the sugar and cinnamon and set aside.On a cutting board, cut the tortillas into triangles.
2. Brush both sides of each tortilla with the melted butter.Sprinkle both sides of each tortilla with the cinnamon sugar mixture.
3. Place on a baking sheet and bake for 10-15 minutes or until crisp.
4. Remove from the oven and set aside to cool.Meanwhile, combine the fruit together in a large bowl. Stir in the lemon juice and top with yogurt if desired.