Helpful tip: Tortillas will fry better when dry, so I like to place them on an ovenproof rack and bake them at 250°F for 5 to 10 minutes or until dry but not at all crisp. This is especially helpful with bags of older tortillas which, when stored in the fridge, often retain moisture. You may skip this step altogether with fresh tortillas that feel dry to the touch.
To fry the tortillas: Pour oil into a frying pan to about a quarter inch depth. Heat over medium-high heat until very hot but not smoking. Tip: If you use your smallest skillet that accommodates the width of the tortilla, you’ll need less oil.
Using metal tongs, fry one tortilla at a time, using the tongs to ensure the tortilla is submerged. The tortilla will immediately develop bubbles. If not, the oil isn’t hot enough. Cook until golden brown on both sides. Use the tongs to peek underneath and flip when lightly golden. Both sides of the tortilla will cook quickly, about 30 seconds total, give or take. When golden on both sides, lift the tortilla out of the pan, letting the excess oil drip back into the pan. The tortilla should no longer be pliable. If not, let the oil heat up more before proceeding with additional tortillas.
Finishing Touch: Place the tortilla on a paper towel-lined plate to absorb the excess oil, and immediately sprinkle with salt to taste.
Tip: If you find the tortillas are browning too fast or the oil starts to smoke, reduce the heat to medium or medium low to allow the temperature to come down. This can happen when cooking multiple tortillas.
To keep the tostadas warm, place them on a baking sheet in a 200°F oven. If you’d like cheese as a bottom layer, you may add it and melt on the tostada this way too.
If you’re making multiple tostadas and get to a point where it’s difficult to submerge the tortillas, simply add more oil to the pan. When adding oil, do make sure to give it time to become hot before cooking another tortilla.