Make the tostadas by coating both sides of the corn tortillas with olive oil cooking spray, then place them on the baking sheet.
Place them in the oven and bake for 5-7 minutes. Flip them over and cook for 2-3 minutes, or until crispy and golden brown.
Remove them from the oven and set aside.
Prepare the pork by removing the silver skin from the pork tenderloin–click here for instructions. Dice the meat into small bite-sized pieces.
Heat the oil in a large skillet over medium-high heat. Add the diced pork, then season with cumin, coriander, garlic powder, oregano, sea salt, and freshly cracked pepper, to taste.
Cook, stirring occasionally, for 5-6 minutes, or until cooked through.
To serve, spread sour cream on the tostada shell, then spoon the pork on top.
Add the lettuce, tomatoes, and avocado, then sprinkle the top with cotija cheese.
Serve immediately with salsa and lime wedges on the side.