Bring a pot of water to a boil; add ancho chile peppers and cook for 5 minutes. Remove from heat and let chiles soak in the hot water until soft, about 10 minutes; drain.

Blend softened chiles, 1 cup vinegar, 15 peppercorns, ginger, 2 garlic cloves, 3 cloves, 1 pinch marjoram, 1 pinch cumin, and 1 pinch thyme in a blender until marinade is smooth. Strain marinade into a bowl.

Place goat in a bowl and pour in marinade, coating goat completely. Cover and refrigerate for 8 hours.

Preheat oven to 350 degrees F (175 degrees C). Transfer goat and marinade to a baking dish; cover with a lid or aluminum foil.

Bake in the preheated oven until goat is very tender, about 3 1/2 hours. Remove lid or foil and cook until goat is browned, about 15 minutes. Pour meat juices into a container and reserve. Cover the goat to keep warm.

Bring a large pot of water to a boil; add tomatoes and boil until soft, 5 to 10 minutes. Drain and let tomatoes cool until easily handled.

Peel tomatoes and place in blender with reserved goat juices, 2 cups water, 3 peppercorns, 2 garlic cloves, 2 cloves, 1 pinch marjoram, 1 pinch thyme, and 1 pinch cumin. Blend until meat sauce is smooth.

Pour meat sauce into a small saucepan and season with salt; bring to a boil. Reduce heat and simmer over low heat.

Bring a pot of water to a boil; add chiles de arbol and boil until soft, about 5 minutes. Drain.

Blend softened chiles with 1/4 cup vinegar, 10 peppercorns, 1 garlic clove, and salt until hot sauce is smooth. Strain into a glass.

Cut goat into bite-sized pieces and serve with a generous amount of meat sauce and hot sauce on the side. Sprinkle onion over goat.