Step 1: Prepare the Chicken Marinade

1. In a large mixing bowl, combine the chicken thighs with the olive oil, lemon juice, garlic, cumin, paprika, turmeric, coriander, cinnamon, allspice, salt, pepper, cardamom, chili flakes, and yogurt. Stir well to coat the chicken evenly.
2. Massage the marinade into the chicken, ensuring all pieces are covered.
3. Cover the bowl with plastic wrap or a lid, and refrigerate for at least 2 hours (overnight for best results).

Step 2: Make the Garlic Sauce (Toum)

1. In a food processor, combine peeled garlic cloves and salt. Pulse to create a smooth paste.
2. Add the egg and lemon juice, then blend again until smooth.
3. Slowly drizzle in the vegetable oil while the food processor is running, allowing it to emulsify.
4. If the sauce becomes too thick, add a tablespoon of ice water to loosen it up. Taste and adjust seasoning with salt and lemon juice if necessary.

Step 3: Cook the Chicken

1. Preheat a grill or skillet over medium-high heat.
2. If using a grill, place the marinated chicken on the grill and cook for 6-7 minutes per side, until browned and cooked through.
   • If using a skillet, heat a bit of oil in a large pan. Add the marinated chicken and cook for 6-7 minutes per side, until golden brown.
3. Rest the chicken for about 5 minutes before slicing it thinly.

Step 4: Assemble the Shawarma

1. Warm the pita or flatbread on the grill or in a dry pan for about 30 seconds per side.
2. Lay the bread flat and place the sliced chicken in the center.
3. Drizzle generously with garlic sauce, and add sliced tomatoes, cucumbers, and onions. Optionally, add pickles for extra tanginess.
4. Garnish with fresh parsley, then roll up the bread to enclose the chicken and veggies.
5. Serve immediately and enjoy your homemade Lebanese Chicken Shawarma!