The meat. Cut the meat into thin, long pieces (about 2 inches long). It will be easier to cut it if you put it in the freezer 30 minutes in advance. Place the beef strips into a bowl together with the onion and garlic. Add the black pepper, cinnamon, allspice, cardamom, nutmeg, and salt and toss to combine.
In another small bowl, whisk together the vinegar and 6 tablespoons olive oil. Add to the meat. Cover and marinate for at least 3-4 hours (24h is better) in the fridge.
Remove the meat from the bowl and dry on paper towels. Discard the marinade. Heat the remaining 4 tablespoons olive oil in a skillet over medium heat and fry the meat for 3-5 minutes.
The sauce. Add the garlic to a food processor and pulse until finely chopped. Add the tahini, lemon juice, parsley, and 3 tablespoons water and pulse again to combine. Season with salt.
The assembly. Split open the pita bread and add some meat slices, tomato slices, pickles, and the Tarator sauce inside. Repeat with remaining sandwiches. Enjoy!