Using a round cookie cutter, cut 3 tostada rounds from each tortilla.
Heat a small skillet on low to medium heat and add the canola oil. Put one of the scraps from cutting the tortillas into the skillet to test the oil. When the oil starts to bubble, remove the test scrap and put a few of the tostada shells in the pan.
As soon as the bottom sides of the shells are a golden color turn them over. When both sides are a golden color remove them from the skillet and lay them on to a paper towel-lined plate.
Sprinkle salt on top. Finish cooking the rounds in batches. Set aside.