1 Cook the onions, garlic, mushrooms, and beans: Heat 2 Tbsp olive oil in a large sauté pan on medium high heat. Add the onions, garlic, and sliced mushrooms. Cook until onions are translucent, but not browned, and the mushrooms have given up some of their moisture, about 5 minutes.
Stir in the refried beans and epazote (if using). Cook for another 3 or 4 minutes. Remove from pan into a bowl, set aside.
2 Cook the chorizo: While onions and mushrooms are cooking, heat 1 tablespoon of olive oil in another, smaller sauté pan or cast iron skillet on medium heat.
Add the chorizo (out of its casing), breaking it up into chunks. Cook for about 5-6 minutes until cooked through and lightly browned. Remove from pan into a bowl and set aside.
3 Make the sauce: In a blender, blend together the chopped tomato, 2 cloves garlic, 1/2 serrano chile, 1/2 cup of water, and a pinch of salt. Blend until smooth.
Pour the sauce into a saucepan and cook on medium high heat until cooked through, bubbly and thick, 4 to 5 minutes. Remove from heat and put into a small bowl, set aside.
4 Fry the plantain: Peel the plantain, slice it on the diagonal in 1/4 inch thick slices. Heat 3 tablespoons of olive oil in a large sauté pan on medium high heat.
Line the pan with the plantain slices. Brown on one side, then flip and brown on the other side. Remove the plantain slices to a paper towel-lined plate, reserving the oil in the pan.
5 Cook the tortillas: Continue heating the oil on medium high heat. One at a time, cook the tortillas. Place a tortilla in the pan and cook until lightly browned and bubbles are forming in the tortilla.
Flip over and cook until lightly browned on the other side too. Continue to cook until the tortilla is somewhat stiff.
Use tongs to remove to a paper towel lined plate and continue the same process with the other tortillas. You will need to add more oil, make sure it heats up before adding another tortilla to the pan.
6 Fry the eggs, sunny side up: Heat a couple tablespoons of olive oil in a stick-free sauté pan (cast iron will work fine).
Crack the eggs into the pan and cook, sunny side up, until egg whites are cooked and the yolks are still a little runny.
7 Assemble the dish: Place a cooked tortilla (tostada) on a large serving plate. Spread some beans over the tostada.
Place a fried egg or two over the beans. Line the outside of the tostada with fried plantain, some chorizo.
Put some salsa over the egg. Put sliced avocado on top of that. Sprinkle crumbled queso fresco over everything. Sprinkle everything with fresh chopped cilantro.