Wash and prepare apples. Place in a medium-sized bowl and stir in yogurt.
Mix sugar and cinnamon in a small bowl or cup.
Pour 1 teaspoon of vegetable oil into a small dish.
Lay the tortilla flat on a large plate. Dip your clean fingers into the oil and lightly coat one side of the tortilla. Once coated, sprinkle lightly with the cinnamon sugar.
Flip tortilla over so the un-oiled side is up. Fill with a quarter of the apple mixture and fold in half.
Heat 2 teaspoons of oil in a large frying pan over medium heat.
Place folded tortilla in pan. Cook until lightly browned, about 1 minute. Flip to cook second side for 1 minute.
Remove from pan, cool slightly, and cut in half. Repeat with remaining tortillas.