Cut open the chilies and discard the veins and seeds.
Put them in a pan and cover with water.
Turn up the heat to bring the water to a boil and then turn it off.
Let the chilies soak for 15 minutes.
Now add the tomatoes to the pot whole and add more water to cover.
Simmer for 15 minutes.
Blend the chilies and tomatoes with a little bit of the cooking water so you get a runny paste.
This will be your chili base. Set it aside for now.
Put the chicken in the pot and add the whole onion and garlic as well as 8 cups water.
Cook for 15 minutes.
Add the corn, epazote and chayote and cook for 15 minutes.
Add the zucchini and beans then strain the chili base into the pot too.
Bring the stew to a boil and skim off any foam on top.
Simmer for 20 minutes then add a teaspoon salt or to taste.
Discard the onion, garlic and epazote then serve with lime wedges and corn tortillas.