In a large skillet over medium-high heat, brown the ground beef and diced onion until meat is cooked through (about 6-8 minutes). Drain excess grease.

Reduce heat to medium-low. Add minced garlic and cook for 30 seconds. Stir in taco seasoning, green chiles, and beef broth. Simmer for 3-5 minutes until liquid absorbs. Remove from heat.

Warm the flour tortillas in the microwave for 20-30 seconds under a damp paper towel to make them pliable.

Place about 1/2 cup of the beef mixture and 1/3 cup of shredded cheese near the bottom center of a tortilla.

Fold the bottom over the filling, fold in the sides, and roll tightly to form a sealed cylinder. Secure with a toothpick if necessary. Repeat for remaining tortillas.

Heat 1 inch of oil in a deep skillet to 350-375°F (175-190°C).

Carefully place chimichangas seam-side down in the hot oil. Fry for 1-2 minutes until golden, then flip and fry for another 1-2 minutes until all sides are crispy.

Remove from oil and drain on a wire rack or paper towels. Top with sour cream, diced tomatoes, and cilantro before serving.