Cook Beef:
In a large skillet, cook ground beef and chopped onion over medium heat until beef is browned and onion is tender. Drain excess fat. Stir in taco seasoning and a little water as directed on seasoning packet. Simmer for 5 minutes.

Mix Filling:
In a bowl, combine cooked rice, refried beans, and half of the shredded cheddar cheese.

Assemble Enchirito:
Spread a few tablespoons of enchilada sauce in the bottom of a baking dish. On each tortilla, spread a layer of the beef mixture, then the rice and bean mixture, and top with a spoonful of enchilada sauce. Roll up tortillas and place seam-side down in the dish.

Add Toppings:
Pour remaining enchilada sauce over the rolled tortillas. Sprinkle with remaining cheddar cheese and sliced black olives, if using.

Bake:
Bake at 350°F (175°C) for 20–25 minutes, or until cheese is melted and bubbly.

Serve:
Top with sour cream and chopped green onions before serving.