Steak Fajitas with Green Sauce from Saveur

¼ cup fresh lemon juice
¼ cup pineapple juice
¼ cup sherry
¼ 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
½ cup sour cream
¼ 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

INSTRUCTIONS

1. 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.
2. 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.
3. 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.