Lightly brush both sides of each corn tortilla with vegetable oil.
Place on baking sheet. Season with cumin to taste, if desired.
Bake for 4 minutes. Flip, and continue baking for 4 more minutes. Check to see if they are crisp. If they are, remove them from the oven. If not, flip them again and continue baking until crisp. NOTE: Keep a very close eye on these as they can burn quickly once they have crisped up.
Once the tostadas cool, they are ready to eat. Top them with a variety of toppings for an easy entree or gobble them up with salsa or guacamole as a snack. Enjoy!