1-First Step: Gather tools and do mise en place.
* Have a 3.5-inch circle cutter or biscuit cutter ready to cut tortilla rounds. Prepare a shallow bowl with the cinnamon-sugar mix.
* Measure 1 cup oil and pour into a deep skillet or frying pan so it reaches about 1 1/2 inches up the side. Set out tongs, a slotted spoon or spider, and a baking sheet lined with paper towels for draining shells.
* If using canned filling, open a 21-ounce can and coarsely chop the filling so it fits neatly into the shells.

2-Second Step: Cut tortillas and make the cinnamon-sugar coating.
* Cut each large flour tortilla into 3.5-inch circles, making about 5 circles per tortilla. This will yield roughly 30 rounds from 6 tortillas; you may not use all rounds if you want fewer tacos.
* Mix ⅔ cup granulated sugar with 2 teaspoons cinnamon in a shallow bowl. This will be used immediately after frying.

3-Third Step: Heat oil and test temperature.
* Heat the oil over medium heat until it is bubbly and about 350°F. If you have a candy thermometer, use it to watch the temperature. Proper oil temperature prevents tough shells.
* Work in small batches so the oil remains hot. If the oil gets too cool, shells will absorb oil and become soggy.

4-Fourth Step: Fry tortilla rounds into taco shells.
* Place one tortilla circle into the hot oil and fry for about 5 seconds. Flip and fold in half using tongs, holding for another 5 seconds so the fold sets. Flip again and fry until the shell is crisp and lightly browned on both sides.
* Remove with a slotted spoon, shake off excess oil, then immediately toss the hot shell in the cinnamon-sugar mixture until evenly coated.
* Cool shells on a pan or wire rack. Store at room temperature uncovered if warm to keep them crisp. These store well up to 3 days.

5-Fifth Step: Make the apple filling (choose one option).
* Filling Option 1: Canned
* Chop 21 ounces apple pie filling coarsely and warm gently in a saucepan over low heat for 1 to 2 minutes to remove excess chill. Drain any extra liquid if needed so the filling is spoonable but not watery.
* Filling Option 2: Homemade (fresh apples)
* Toss 3 large peeled, diced apples with 1 teaspoon fresh lemon juice to prevent browning.
* In a skillet over medium heat, melt 1 1/2 tablespoons butter. Add the apples, 1 teaspoon cinnamon, 3 tablespoons brown sugar, and 1/4 cup water. Cook for about 4 minutes, stirring occasionally so apples start to soften.
* Mix 1 teaspoon cornstarch with the remaining 1/4 cup water until smooth, then stir into the apple mixture. Cook until the liquid mostly evaporates and the apples are tender but not mushy. Remove from heat and cool slightly.

6-Final Step: Assembly and serving.
* Fill each cooled shell with about 2 tablespoons of pie filling. Top with frozen whipped topping or a scoop of vanilla ice cream.
* Drizzle caramel sauce if desired, and sprinkle a touch more cinnamon-sugar for sparkle.
* Serve immediately in a taco holder or an overturned tin lined with a cloth napkin so the tacos stay upright.