Preheat oven to 350°F.
Brown ground beef in a large pan. Drain fat. Add water and taco seasoning. Simmer 5 minutes or until thickened.
Meanwhile, heat refried beans (in microwave or stovetop) and prepare Topping ingredients.
Place tostada shells in the oven and bake 5 minutes or until warmed and fragrant.
Remove from the oven and gently spoon heated refried beans onto tostada shells. Top with a spoonful of ground beef, and toppings as desired. Serve immediately.
Recipe courtesy of SpendWithPennies