In a medium skillet over medium heat, add pork, salsa, garlic & onion powders, chili powder, cumin, and salt and pepper. Stir to combine and cook until heated through. Add additional salsa if needed.
Heat refried beans in a small skillet over medium heat until warmed through.
Spread tostadas with refried beans, then top with shredded pork mixture. Finish with lettuce, tomatoes, avocado, queso fresco, and additional salsa verde, hot sauce, and a squeeze of fresh lime juice if desired.
This recipe is based off using leftovers from my All Purpose Slow Cooker Pork Roast. If you do not have that you could use shredded cooked chicken or other protein of choice.