Heat a skillet over medium heat and briefly pan-fry the prepared shredded beef for 1–2 minutes, stirring, to remove excess moisture and warm it through; set aside.
Warm a flour tortilla in the skillet over medium heat for about 10–20 seconds per side until soft and pliable.
Place the warmed tortilla on a plate and spoon about 3/4 cup of the shredded beef into the center, leaving a couple inches of space around the edges.
Fold the two short (horizontal) sides of the tortilla inward, then roll from one long side to the other to form a sealed burrito-style chimichanga.
Using a pastry brush, lightly coat the entire outside of the rolled chimichanga with olive or avocado oil.
Place the chimichanga seam-side down in the air fryer basket and air fry at 375°F for 10 minutes.
Carefully flip the chimichanga and continue air frying at 375°F for an additional 6–10 minutes until golden brown and crisp.
Transfer to a serving dish and top with chopped tomatoes and sour cream (crema) or other desired toppings.
