Heat a skillet over medium-high heat. Add ground beef and break it apart with a spoon.
When the beef starts to brown, add chopped onion and cook until soft (about 3–4 minutes).
Stir in minced garlic, chili powder, cumin, smoked paprika, salt, and pepper. Cook for another minute.
Add salsa or enchilada sauce, stir to combine, and remove from heat. Taste and adjust seasoning if necessary.
Warm each tortilla for 10 seconds on each side in a dry skillet or microwave. Stack them and cover with a kitchen towel to keep warm.
Place a warm tortilla on a surface, then spoon about ⅓ to ½ cup of the beef mixture in the center. Add ¼ cup of cheese and a tablespoon of cilantro (optional).
Fold the sides of the tortilla towards the center and roll tightly from top to bottom, sealing the ends with a little water.
To fry: Heat oil in a heavy skillet to 350°F. Fry chimichangas for 2–3 minutes on each side until golden brown.
To bake: Preheat the oven to 425°F. Arrange chimichangas on a baking sheet and bake for 15–20 minutes, flipping halfway through.
Once cooked, serve with salsa, sour cream, or crema, and sprinkle with fresh cilantro or green onions.