For the chimichurri:
1/2 cup packed fresh parsley leaves
1/2 cup packed fresh basil leaves
1/4 cup packed fresh cilantro leaves
1/4 cup extra-virgin olive oil
2 garlic cloves, finely minced
2 teaspoons white wine vinegar
1 tablespoon lime juice
1/2 teaspoon ground coriander
1/2 teaspoon ground cumin
1/2 teaspoon salt
1/8 teaspoon freshly ground black pepper
For the steak:
1/2 teaspoon chili powder
1/2 teaspoon salt
1/4 teaspoon black pepper
Ground cayenne to taste (1/8 to 1/4 teaspoon)
1 1/4 pounds skirt steak
Preheat the broiler and coat a broiler pan with cooking spray.
For the chimichurri: Combine the parsley, basil, cilantro, olive oil, garlic, vinegar, lime juice, coriander, cumin, salt, and pepper in a blender. Process, shaking the blender if needed, until smooth, 2 to 3 minutes.
For the steak: Combine the chili powder, salt, black pepper, and cayenne, and sprinkle the mixture evenly over both sides of the steak. Place the steak on the prepared rack and broil 3 to 4 minutes per side for medium rare. Transfer to a cutting board and allow the meat to rest 5 minutes. Cut across on the diagonal into 1/4-inch to 1/2-inch wide strips. Serve drizzled with the chimichurri sauce.