Put the chiles and tomatoes in a small saucepan. Add chicken broth and water. Boil for 10 minutes.

Heat some oil in a small skillet. Add the onion and garlic and saute until softened, about 10 minutes.

Put the contents of both pans into the blender. Add the epazote and blend until smooth.

Pour the sauce back into the small saucepan and cook over low heat for 30 minutes.

Mix the masa and water together and let rest for at least 10 minutes. Increase the heat on the molé so it is bubbling and then slowly add the masa slurry to the molé while stirring. Cook as it thickens, stirring constantly, about 5 minutes.

Stir in the shrimp and cook for 5 minutes. Plate right away.