Ingredients
1/4 cup fresh lemon juice
1/4 cup pineapple juice
1/4 cup sherry
1/4 cup soy sauce
3 tbsp. butter, melted
1 tbsp. freshly ground black pepper
3 whole dried chiles de árbol, crushed
1 clove garlic, finely chopped
Zest of 2 lemons
Zest of 1 orange
2 skirt steaks (about 3 lbs.), trimmed and halved
crosswise
6 tomatillos, husked and rinsed
2 small serrano chiles, stemmed
2 ripe avocados, such as hass, gwen, or frey, peeled,
seeded, and chopped
1/2 cup sour cream
1/4 cup chopped cilantro leaves
Salt
6 tbsp. canola oil
2 red bell peppers, cored, seeded, and thickly sliced
2 yellow onions, thickly sliced
Warm flour tortillas
Preparation
Combine fruit juices, sherry, soy sauce, butter, pepper, chiles de árbol, garlic, and zests in a large dish; add steaks; turn to coat. Cover; marinate for 2 hours.
Bring a large pot of water to a boil. Add tomatillos and serrano chiles and cook until tender, 8-10 minutes. Drain and transfer to a blender. Add avocados; blend until smooth. Transfer to a large bowl and stir in sour cream, cilantro, and salt to taste. Cover surface with plastic wrap and refrigerate.
Heat 3 tbsp. oil in a large cast-iron skillet over medium-high heat. Add peppers, onions, and salt to taste. Cook, stirring occasionally, until softened and beginning to char, 8-10 minutes. Transfer to a plate and set aside. Wipe out skillet. Heat 1 tbsp. oil in skillet over medium-high heat. Working in batches, cook steaks, flipping once, until well browned, adding remaining oil as needed, 7-8 minutes per batch. Transfer to cutting board, tent with foil, and let rest for 10 minutes. Cut steaks crosswise into finger-size strips. Transfer to a platter, along with collected juices and peppers and onions. Serve with tortillas and green sauce.