Make the Green Chile Pesto First: Coarsely chop the peppers and place in a food processor. Add the 1/2 cup cilantro leaves, 1/4 cup Cotija cheese, 2 tablespoons pine nuts, 2 cloves garlic, and 1/4 teaspoon crushed red pepper.
Process in the food processor until finely chopped. Season with salt and black pepper to taste. Then with processor running, add 1/3 cup oil in a steady stream through feed tube to form a coarse paste.
Pour pesto in a medium bowl, cover and refrigerate until needed. This pesto can be made up to a day in advance of serving.
For the Flank Steak: Trim fat from steak. Score both sides of the steak in a diamond pattern by making very shallow diagonal cuts at 1-inch intervals.
In a bowl combine all the seasonings- 2 tsp. chili powder, 1 tsp. salt, 1 tsp. espresso powder, 1/2 tsp. garlic powder, 1/2 tsp. oregano, 1/2 tsp. black pepper. Sprinkle mixture over both sides of steak; rubbing in with fingers.
Coat an extra-large nonstick skillet with the oil; heat skillet over medium-high heat. Add steak; reduce heat to medium.
Cook 12 to 14 minutes for medium rare (145F degrees) or 14 to 16 minutes for medium (160F degrees), turning once.
Thinly slice the steak across the grain. Serve with the Green Chile Pesto. If desired, sprinkl with cilantro.