01 -
Drizzle olive oil into the bottom of the slow cooker and layer the sliced red onions over it.
02 -
Place the beef chunks over the onions. Add minced garlic, lemon juice, oregano, salt, and black pepper on top.
03 -
Cover the slow cooker with its lid and cook on low for 8 hours.
04 -
Once cooked, remove the lid and shred the beef using two forks.
05 -
If desired, warm the pita breads in a skillet. Serve shredded beef on the pitas, topping with diced onion, tomatoes, cucumber, shredded lettuce, and tzatziki sauce.