Cook the chicken breast and shred it.

Fry the onion until transparent, then add the minced garlic and 2 tomatoes, and set aside.

Blend the remaining tomatoes with the chipotle peppers and a bit of the chicken broth.

In a pan, combine the blended mixture with the grated carrots, chicken, and the tomatoes with onion that we fried. Bring to a boil and season with salt and pepper.
Spread refried beans on the tostadas, serve the chicken, garnish with avocado, and you're done. Serve with your favorite salsa.