Preheat oven to 400 degrees. Microwave 4-6 burrito-sized tortillas for about 30-45 seconds until warm and pliable. Place oven-safe jars upside down on a cookie sheet. With your hands, rub oil on tortillas so they are well coated. (This helps them crisp up and prevents them from sticking to the jars.) Drape tortillas over jars and bake for 8-10 minutes until they are crisp and slightly brown.
Yup, that's it. Enjoy!