Begin by heating the olive oil in a frying pan over medium heat. Once hot, add the corn tortillas one at a time, frying them for about 2-3 minutes on each side, or until they are golden brown and crispy. Remove them from the oil and place them on a paper towel to drain excess oil.
In a large skillet, add the chopped onion and garlic. Sauté over medium heat until the onion is translucent, about 3-4 minutes. Add the ground beef, breaking it apart with a spatula. Cook until browned, stirring frequently. Once the beef is cooked, stir in the taco seasoning and kosher salt, mixing well to combine.
In a small saucepan, heat the refried beans over low heat until warm, stirring occasionally. This will create a delicious spreadable layer for your tostadas.
Spread a generous layer of refried beans on each crispy tortilla. Top with the seasoned ground beef, followed by a handful of shredded iceberg lettuce, halved cherry tomatoes, and chopped avocado. Sprinkle with crumbled cotija cheese and fresh cilantro.
Serve your Mexican Tostadas immediately while the tortillas are still crispy. Enjoy them with your favorite salsa or hot sauce for an extra kick!