Oven Tacos

2 lbs ground beef 
1 small onion diced
1 small can diced green chilies
1 packet taco seasoning
1 can tomato sauce 
1 (16 ounce) refried beans (optional)
2 cups shredded cheese (I used Mexican Style Cheese)
18-20 hard taco shells 

Optional Condiments- 
Shredded Lettuce  
Tomatoes  
Salsa 
Sour Cream

Preheat the oven to 400 degrees.  

In a large skillet brown ground beef and onion over medium-high heat. Drain off any excess liquid. Return to pan, add chilies, refried beans, tomato sauce, and taco seasoning. Mix well and cook for a few minutes if mixture seems runny. 

Spoon the taco meat mixture into the taco shells and place into a 9 x 13 inch baking dish, standing up. Sprinkle cheese over the top of the taco meat in each shell. Place into the oven and bake at 400 degrees for 10-12 minutes or until the cheese has melted and the tacos are heated through. 
Remove from the oven and top with any optional condiments for serving.