Heat the cooking oil in a skillet over medium heat. Once hot, add the corn tortillas one at a time, frying them until they are golden and crispy on both sides. This should take about 1-2 minutes per side; be careful not to burn them! Once done, place them on paper towels to drain excess oil.
In a large bowl, combine shredded chicken with taco seasoning mix and salsa. Stir well until all ingredients are evenly coated with salsa and seasoning.
Fold in the rinsed black beans and drained corn into the chicken mixture. Ensure all ingredients are mixed thoroughly.
Take each crispy tortilla and layer it generously with the chicken mixture followed by a sprinkle of shredded colby jack cheese on top.
Top each assembled tostada with fresh diced tomatoes and cilantro leaves for brightness and flavor contrast.
Serve your tostadas warm with wedges of lime on the side for squeezing over the top before eating.