1. Preheat the oven to 425°F and line a baking sheet with parchment paper.

2. In a skillet over medium heat, cook the ground beef and chopped onion until the beef is browned and the onion is soft.

3. Stir in the garlic, taco seasoning, tomato sauce, salt, and black pepper, then cook for 2 to 3 minutes until the mixture is thickened.

4. Remove the skillet from the heat and let the beef mixture cool slightly.

5. Warm the tortillas so they are soft and easy to roll without cracking.

6. Spoon some beef filling onto each tortilla and top with shredded cheddar cheese.

7. Roll each tortilla tightly and place it seam-side down on the prepared baking sheet.

8. Brush or lightly spray the taquitos with olive oil.

9. Bake for 15 to 18 minutes, or until the taquitos are golden brown and crisp.

10. Serve hot with chopped cilantro, sour cream, salsa, and diced tomatoes.