Start by slicing your white mushrooms, red onion, red bell pepper, and beef sirloin tip steak into thin strips. Mince the garlic cloves and set everything aside.
In a large skillet, heat the olive oil over medium heat. Add the sliced red onion and red bell pepper, cooking until softened, about 4-5 minutes. Then add the mushrooms and minced garlic, stirring occasionally, until everything is tender and fragrant.
Push the vegetables to the side of the skillet and add the thin strips of beef sirloin tip steak. Season with salt, black pepper, and dried oregano. Cook the steak for about 3-4 minutes, stirring frequently until it’s browned and cooked to your desired doneness.
Once the steak is cooked, remove the skillet from heat. Take the pita pockets and gently open them up. Place a few torn romaine lettuce leaves inside each pocket, then spoon in the steak and vegetable mixture generously.
Top each sandwich with a dollop of plain nonfat Greek yogurt. This will add a creamy texture and a touch of tanginess that complements the savory filling perfectly.
Serve your Steak Fajita Sandwiches warm, and enjoy the burst of flavors with each bite. They are perfect for a casual meal or even served at a small gathering.
