Tostadas are full of components, the filling (in this case, squash) the beans, the tortillas, the slaw…..but all those layers of tastes and textures are the precise reason that tostadas are so much fun to eat.
The truth is, all you really need to make is the roasted squash and the tortillas, the other stuff is just extra. I mean, hell, if you are really feeling muy autentico you could go ahead and make guacamole, Spanish rice, and maybe even a margarita or two—you will need something to wash this all down with after all.
Note: I use hot Peri-Peri spice mix to season the squash, but you could use any spice mix you like, Lawry’s, or Old Bay would be great or just use freshly ground black pepper instead.
Heat oven to 450°F. Combine squash, olive oil, salt and spice mix on a baking sheet and toss until squash is well coated. Roast until squash is soft and starting to brown, about 15 to 20 minutes. Remove from oven and set aside. (This can be served warm or at room temperature.)
For the Beans:
Heat oil in a small saucepan over medium heat. Add onions and garlic and season with salt and pepper. Cook, stirring occasionally, until onions are translucent.
Add beans (juice and all), cumin, coriander, and oregano. Bring to a boil, then reduce heat to a simmer. Using a potato masher, or the back of a large spoon, mash beans until almost all are broken up. Let simmer until thick, about 5 minutes. Taste and add more salt if necessary.
For the Tortillas:
Heat oil in a large cast iron skillet or heavy frying pan over medium heat. The oil will need to reach about 325°F to 350°F. If you don't have a deep fat thermometer, place a wooden chopstick in the oil, if bubbles cover the chopstick almost immediately you know it's hot enough. Meanwhile, line a large plate with paper towels and set aside.
Place one tortilla at a time into the hot oil. Hold the tortilla under the oil with tongs until the bottom is golden brown, about 2 minutes. Flip and fry the other side until golden, about another minute.
Remove to paper towel-lined plate and sprinkle with kosher salt. Repeat with remaining tortillas. (If the tortillas seem to be cooking too fast, lower the heat, or raise it if they seem to be taking too long to brown. You may need to do this a couple times while frying)
I like to place all the components on the table and let my family build their own tostadas. I also place bowls of lime wedges, avocado slices and bottles of hot sauce out for garnish. You can also garnish the tostadas with crumbled queso fresco (or feta cheese), cilantro leaves and sliced radishes.
If you want to serve the tostadas already made: take a tortilla and spread some beans on one side, a couple tablespoons full will do. Top with about 1/4 cup of the squash and a small mound of slaw.