Place the ground beef and chopped white onion in a skillet on the stove top. Cook on medium heat, and break up the beef into bite-size pieces. Once the beef is cooked (about 5 minutes), sprinkle the taco seasoning on top of the beef. Add the water to the skillet and mix well. Simmer on low for 5 minutes.
While beef is simmering, heat the refried beans on the stove top on low heat until warm and pliable.
Preheat the oven to 400 degrees Fahrenheit.
Place taco shells in a large glass baking dish. Layer with ground beef and a tablespoon of refried beans until all the beef and beans are used up. Then sprinkle the cheese on top of the tacos and bake the tacos for 10 minutes until shells are golden in color and cheese is melted.
Carefully, remove from the oven and top with your favorite toppings like shredded lettuce, pico de gallo, sour cream, and guacamole!