Heat the 1 tablespoon avocado oil in a skillet over medium heat. Using tongs to rotate it, sear all sides of the beef until just crispy brown. This step is optional but add lots of flavor. Set this pan aside to use later.
Place the seared beef and the remaining beef ingredients to the crock of a slow cooker. Cook on low heat for 8-12 hours.
Lay a few paper towels on a plate; set aside.
In the skillet you seared the meat in, add another 2 tablespoons avocado oil and preheat it over medium-low heat. You know it's ready when you insert a wooden spoon's handle and the oil bubbles.
As the oil is heating up, microwave the tortillas for about a minute (if you have a tortilla warmer, use that). If you don't have a microwave, wrap the tortillas in a damp towel and pop in the oven on a sheet pan on the lowest possible heat until the tortillas are warm and pliable.
Add about ¼ to ½ cup of the meat to each warm tortilla (shake off excess liquid) and fold it shut.
Place as many chimichangas as will fit seam-side down in the preheated oil. Cover with a splatter screen so oil doesn't go everywhere.
Allow to pan fry for 2 or 3 minutes or until desired golden brownness; using tongs, flip the chimichangas to the top and repeat pan frying for 2 or 3 minutes or until desired golden brownness. You can also pan fry the sides and ends by either holding them in the oil or leaning them against the side of the skillet. Please remember than any juice that leaks out into the oil will cause it to sputter, so be very careful.
Remove the chimichangas from the oil and set on the paper towel lined plate to allow excess oil to drip off. Continue frying the remaining chimichangas until all are done.