To make the tomato sauce, toast the tomatillos, tomato, onion and garlic in a clean sauté pan over medium-high heat, for 8 to 10 minutes, turning every few minutes until they are brown on several sides. Once toasted, remove from heat and place in a food processor or blender and set aside.
Toast dried chiles in the same pan over medium high heat for 3 to 4 minutes, until they are browned and fragrant. Add to tomato mixture. Toast sesame seeds in the same skillet over medium heat, taking care not to burn them, about 4 to 5 minutes. The seeds are done when they are deeply golden and popping. Add to tomato mixture.
Toast pepitas over medium heat, again in the same skillet until they are deeply golden and popping, about 7 to 8 minutes. Add to tomatoes and sesame seeds. Add cilantro to the pan and cook quickly, about 2 minutes. Add to tomato mixture.
Add salt to tomato mixture, starting with one teaspoon. Blend until mixture is combined and very smooth. You will need to add about 1/4 to 1/2 cup of water to the mixture to thin out the sauce. Taste for salt and add more to your liking (for this amount of sauce, I like two teaspoons). Set aside while the soup simmers.
To make the soup, in a large stockpot, add pork ribs and cover with 2 inches of water. Bring to a boil, turn heat down, cover and simmer for 1 hour. Add chicken pieces, carrots and güísquil. Bring back to a boil, reduce to a simmer, cover again and simmer another 30 minutes.
Add potatoes and güicoy to the stockpot. Remove enough water from the pot until remaining liquid covers ingredients inside. You are making room for the tomato sauce. Add sauce from the blender to the stockpot, bring to a boil again, and allow mixture to simmer, uncovered, for 20 minutes. Broth should be a thick stew quality. Turn off heat.
To serve, place cooked rice in bowls, about a 1/2 cup each. Ladle chicken, pork, or both into bowls with plenty of vegetables and about 1/2-2/3 cup of broth. Sprinkle with cilantro and serve with tortillas de maiz.