Created by ellie on November 1, 2017
Step 1: Preheat the grill to medium hot.
Step 2: In a bowl combine the marinade ingredients (vinegar - garlic plus 1 teaspoon each of salt and pepper). Whisk in 3/4 cup of the oil in a steady stream until emulsified. Put the flank steak and half of the marinade (2/3 cup) in a plastic bag, seal and refrigerate for 30-60 minutes.
Step 3: Drizzle peppers with the remaining 1 tablespoon oil and grill until blackened all over (10-15 minutes). Put the peppers in a small bowl, cover immediately with plastic wrap, and let steam until cool.
Step 4: Remove steak from the marinade and pat dry. Sprinkle with 2 teaspoons of salt and pepper. Grill steak (6-8 minutes per side) for medium rare. Remove from grill, cover with foil and let rest 15 minutes.
Step 5: Meanwhile, core, seed, and peel the cooled peppers and slice them into thin strips. Strain the reserved marinade through a fine sieve. Warm pitas on the grill, flipping once after 2 minutes for a total time of 4-5 minutes. Transfer to a plate and cover with foil to keep warm.
Step 6: To assemble: slice the steak thinly on an angle across the grain. Put a few slices of beef and some of the roasted red peppers, red onion, spinach and feta on each pita. Drizzle with 1 tablespoon of the strained marinade and fold. Repeat for all ingredients.