Step 1

Position a rack in the middle of the oven and preheat to 450 degrees.

Step 2

Use a teaspoon to scrape the dark gills from the underside of the mushroom caps; discard that material. Cut the caps into 1/4-inch slices.

Step 3

In a large nonstick skillet over medium heat, heat 2 tablespoons of oil until it shimmers. Add the mushrooms, poblanos, onion and 1/2 teaspoon of salt. Cook, stirring, until the vegetables have lightly browned and softened, 8 minutes. Transfer to a bowl and cover to keep warm.

Step 4

Increase the heat to medium-high, and add 2 tablespoons oil to the same skillet, heating it it shimmers. Add the beans and coriander and cook, mashing with a fork or a potato masher, until the mixture resembles a coarse puree and begins to brown at the edges, about 3 minutes.

Step 5

Stir in the reserved bean liquid and cook, stirring constantly, until the beans are dry, about 1 minute. Remove from the heat, then stir in the remaining 1/4 teaspoon of the salt and the pepper, the pickled jalapeños and pickling liquid. Taste, and season with more salt, as needed.

Step 6

Arrange the top and bottom halves of the rolls cut sides down on a sheet pan. Brush with the remaining 1 tablespoon of oil and bake until crisp and golden brown, 3 to 5 minutes. Transfer the tops to a large plate and turn the bottom halves, cut sides up. Leave the oven on.

Step 7

Spread equal amounts of the bean mixture on the cut sides of each bottom roll. Top with the poblano-mushroom mixture, followed by the cheese. Bake until the cheese begins to melt, 3 to 5 minutes.

Step 8

In a medium bowl, use a fork to mash the avocado with the lime juice until combined and spreadable.

Step 9

Spread the avocado mixture on the cut sides of the top halves of the rolls, then place those on top of the tortas, and serve warm.