1. Microwave the flour tortillas wrapped in a damp paper towel for about 30 seconds to make them pliable.
2. In a skillet over medium-high heat, cook the ground beef until no pink remains (about 8-10 minutes), breaking it into crumbles. Drain excess grease.
3. Add taco seasoning and water to the beef, stir, reduce heat and simmer until thickened, about 3-4 minutes. Remove from heat.
4. Warm refried beans and enchilada sauce separately.
5. Spread about 2 tablespoons of refried beans down the center of each tortilla. Top with ¼ cup of seasoned beef and sprinkle with 1 tablespoon diced onions. Roll tightly with seam side down.
6. Arrange rolled enchiritos in a lightly greased 9×13-inch baking dish.
7. Pour enchilada sauce generously over the enchiritos, then sprinkle cheddar cheese evenly on top.
8. Bake at 350°F (175°C) for 15 minutes until cheese melts and sauce is bubbly. Alternatively, microwave individual enchiritos with sauce and cheese for 1-2 minutes until warmed.
9. Let rest 5 minutes before serving. Garnish with sliced black olives.