In a large pot, add 3 lb chicken breast cut into bite sized pieces and enough water to cover the top of the chicken. Bring the water to a boil. Once boiling, reduce to a simmer and add 1 ½ tsp salt. Allow the chicken to simmer for about 20 minutes, or until it turns white and is cooked through. Skim off any residue left on top of the water as the chicken is cooking. When the chicken is done cooking, remove the chicken from the water, and reserve the water (now broth).
While your chicken is cooking, heat a cast iron skillet over medium heat. Add ½ cup pumpkin seeds, ½ cup sesame seeds, and 1 cinnamon stick to the dry skillet. Toast the combination until the seeds begin to turn brown. Once toasted, remove the seeds and set aside.
Keeping the skillet over medium heat, add 2 corn tortillas. Toast until brown on one side. Then use tongs to flip over until browned on the other side.
Once the tortillas are toasted, remove them from the heat. Put them in a small bowl with a thin layer of water to soften the tortillas.
Turn the heat on the skillet to high. Once heated, add 5 roma tomatoes into the skillet, and cook, turning, until the skin is charred. Once charred, remove the tomatoes and set aside.
Next, add 1 white onion (skin still on), 1 Chile Pasa (Pasilla), and 1 Chile Guaque (Guajillo). Turn until the skin is charred. Then remove and set aside.
Add the cinnamon stick to a spice grinder and pulse until the cinnamon is finely ground.
In a food processor, add the sesame seeds and pumpkin seeds. Put the lid on the food processor and pulse until finely ground. Remove the ground pumpkin seeds and sesame seeds to a small bowl and set aside.
In the food processor, add the charred roma tomatoes, the onion (still not peeled) the chile pasilla, and the chile guajillo. Add the lid to the food processor, and pulse until ground finely. Add ¼ tsp paprika (or achiote), 1/2 cup chopped cilantro, the ground cinnamon, the sesame seeds, and pumpkin seeds. Pulse together until fully combined.
Add the corn tortillas and 4 cups of the reserved chicken water. Pulse until everything is fully combined and smooth.
Pour the sauce into a large pot and bring it to a low boil. Add the chicken and simmer for 15 minutes.
Serve sprinkled with sesame seeds and with avocado on the side. Enjoy!