In a medium bowl, combine the shredded chicken, lime juice, cumin, chili powder, salt, and pepper. Mix well and set aside to let the flavors meld.
Preheat the oven to 375°F (190°C). Place the corn tostada shells on a baking sheet and warm them in the oven for about 5-7 minutes, or until crispy.
While the tostadas are warming, prepare the toppings. In a small bowl, mix the refried black beans with a pinch of salt and heat them in the microwave for about 30 seconds or until warm.
Once the tostada shells are ready, spread a layer of refried black beans on each shell.
Top the beans with the seasoned shredded chicken, followed by a generous handful of shredded lettuce.
Add diced tomatoes and shredded cheese on top of the lettuce.
Finish each tostada with a few slices of avocado and a dollop of sour cream.
Garnish with fresh cilantro for extra flavor and color.
Notes
Arrange the tostadas on a colorful platter and serve with lime wedges on the side.