Directions:

Heat a gas or charcoal or the broiler.

Brush the mushrooms with the oil and grill or broil, turning once, until browned on both sides. Remove, cut into thin slices, and set aside on a plate.

Place the poblano chiles on the grill or under the broiler and roast, turning, until the skins black on all sides. Place in a bowl, cover with plastic wrap, and allow to steam until cool. Remove the skins, stems and seeds and discard. Cut into thin strips and set aside on the plate with the mushrooms.

Place the sliced onion in a colander, rinse under cold water, and shake well to drain. Place on paper towels and pat dry, then place on the plate with the mushrooms. Place the lettuce leaves, tomatoes, avocado, and feta in piles on another plate close by.

Heat a medium skillet or griddle over medium heat. One at a time, place the tortillas in the dry skillet and warm on each side until they become pliable. Transfer to a work surface. Place a lettuce leaf on each tortilla and top it with 2 tomato slices, a few strips of mushroom and poblano, a few onion slices, 2 avocado slices, and a slice of cheese. Sprinkle with salt and roll up into a tube. Secure with a toothpick if necessary.

To serve, place 2 tacos on each serving plate. Garnish with the chipotle chiles, if using, and sprigs of cilantro. Serve immediately.