In the Dutch oven place the stew meat, garlic cloves, bay leaves, mint and a tablespoon of salt and pepper with half onion. Cover with 10 cups of water and bring to a rolling boil over medium-high heat. Skim off any foam that rises to the surface and reduce the heat to medium-low, cover and simmer for 30 minutes.
Meanwhile, place the ancho and pasilla chilies in a medium bowl, cover with boiling water and let rehydrate for 15 minutes.Place the tomatillos and tomatoes under the broiler on a sheet pan, until they are charred and mushy about 10-12 minutes.
In the blender add the tomatillos, tomatoes, chilies and ¼ cup the soaking liquid. Puree until completley smooth.
Remove the lid from the Dutch oven, remove the cooked onion and the mint and garlic cloves. Add in the chili mixture from the blender to the meat, stir and cover and simmer for another 30 minutes.
Remove the lid from the Dutch oven, raise heat to medium and add in the chayote and the corn and cook partially covered for 15-20 minutes. Add in the green beans and zucchinni and cook partially covered for another `0 minutes, taste for salt and and more if needed.
Serve hot in bowls with cilantro, chopped onion and tortillas