Cook chorizo in a large nonstick frying pan over low heat, mashing, until it starts to brown, about 6 to 8 minutes.
Add the beans and the liquid. Cook over medium heat. While the beans are boiling mash them with a potato masher. Continue to cook until they form a thick paste, about 10 minutes. Add tomato sauce and stir.
In a large sauté pan over medium high heat, add the olive oil and onion. Cook for 10 to 15 minutes, stirring often, until the onion begins to caramelize. Set aside.
Making the Huaraches:
In a mixing bowl combine the masa harina and salt. Add the shortening and using your hands combine until shortening is evenly distributed. Add warm water and knead until mixture is smooth and slightly sticky. If the dough is dry add more water, 1 tablespoon at a time. Dough should be soft and moist like play-doh and not dry. Divide dough into 6 portions. Cover with a damp cloth to keep the dough soft and moist.
Line a tortilla press with plastic wrap. Roll the dough into a cigar shape, about 5 inches long. Place between two sheets of plastic and flatten gently with tortilla press or under heavy skillet until 1/4-inch thick. Peel off the plastic wrap. Repeat with remaining dough.
Preheat an ungreased comal (griddle) on medium-high heat. Cook huaraches on the comal for about 2 to 4 minutes on each side until dry. Repeat with the remaining patties.
Layer the Huaraches:
Preheat broiler. Place huaraches in a single layer on a baking sheet. Layer each huarache with some warm chorizo refried beans, caramelized onions, and sliced tomatoes. Broil in the oven for 5 minutes or until tomatoes are slightly roasted and soft. Garnish with goat cheese, basil, and avocado slices.
To Make Ahead:
Cook huaraches as directed. Place cooled huaraches in a single layer in an airtight container, cover, and seal tightly. Huaraches can be stored for one week in the fridge or in the freezer for one month. If frozen, allow to defrost before preparing. Layer the huaraches and bake as directed above.
Once you have the base for a huarache the choice of toppings are endless. Use your imagination and have fun.Suggestions: