Toast pumpkin seeds in the un-oiled Dutch oven on the stove over medium heat until they begin to swell and brown lightly. Remove from heat and cool, and then grind them finely in a mortar, spice grinder, or food processor.

Cut the onion in quarters and lightly char with tomatillos, Poblano pepper, jalapeño pepper, and garlic cloves over an open flame or in the oven under the broiler. Remove stems, seeds, and most of the blackened skin from the onion, tomatillos, peppers, and garlic. Combine vegetables and Mexican oregano in a food processor and blend to a smooth puree, adding a bit of stock if needed to get everything blended.

Separately, blend the cilantro and epazote with 1 cup of stock and set aside.

Cut up the various toppings and reserve each in a separate small bowl (keep tostadas whole).

Heat the olive oil in the pot and add the onion/pepper/tomatillo/garlic puree. Fry over high heat, stirring until the puree starts to dry out and stick to the pan. Mix in the ground pumpkin seeds for the last minute of frying.

Add the remaining 7 cups of stock to the pot and bring to a simmer on the stove. Add whole chicken breasts and cook over low heat for 20 minutes .

Remove chicken breasts (check that they are fully cooked, and cook a little longer if needed), dice or shred meat and return to pot. Add cilantro/epazote puree and hominy to pot and simmer 10 minutes more. Adjust salt to taste.

Serve in deep bowls with fried tostadas and toppings on the side.