Preheat the broiler or a grill to medium. Drizzle the steak with the EVOO; season with salt and pepper. Cook, turning once, for medium-rare, 8 to 10 minutes. Let cool slightly, then thinly slice.
While the steak is cooking, using a food processor, puree the feta, yogurt, lemon juice, garlic, oregano, cumin, coriander and hot sauce. Season with salt and pepper; transfer to a bowl.
Char the pitas under the broiler or on the grill. Top with the steak and your choice of toppings. Serve with the lemon wedges and yogurt sauce.