Brown ground beef. Drain any excess grease and return meat to pan. (This step is KEY so that your tostadas aren't soggy).
Then add ½ cup of water and taco seasoning. Stir to coat ground beef.
Preheat the tostada shells dry for 3-4 minutes before adding the toppings.
Heat refried beans in microwave for about 30 seconds to make them easier to work with.
Spread a thin layer of refried beans on top of each tostada shell. You want most of the shell to be covered, but don't want a layer too thick that will make the tostada soggy.
Spoon seasoned ground beef onto refried beans.
Add a layer of cheese on top of beef.
Add diced tomatoes, red onions and avocado on top of tostadas.
Bake for 10 minutes or until cheese is melted.
Top with additional avocado or salsa, optional.
Notes
You can smash whole beans to create your own "refried beans" layer, if desired as an alternative to refried beans.If making ahead of time, I recommend keeping the ingredients separate until it's time to eat.Do not add salsa or any other sauces to tostadas until after they've baked so they do not get soggy.