First pat 4 boneless skinless chicken thighs dry and cut each into 2 large pieces. Place all 8 pieces in a large mixing bowl. Then add 3 tablespoons extra virgin olive oil, 2 tablespoons fresh lemon juice and 4 minced garlic cloves. Sprinkle in 2 teaspoons ground cumin, 2 teaspoons smoked paprika, 1 teaspoon ground coriander, 1 teaspoon ground turmeric, 1/4 teaspoon ground cinnamon, 1/4 teaspoon cayenne pepper, 1 teaspoon kosher salt and 1/2 teaspoon freshly ground black pepper. Turn the chicken with your hands or tongs for 1 to 2 minutes until every piece has a thin coat of spice paste. Keep it below 40°F if you're not cooking it right away. The pale pink meat should now look orange-red with small dark flecks and no dry patches of spice. Don't add extra lemon juice just to thin the paste. Too much liquid can make the chicken steam later. The oil helps the spices cling so they won't fall off during roasting.

Cover the bowl and chill the coated chicken at 40°F or colder for at least 30 minutes. You can leave it for up to 12 hours if you're getting dinner ready the night before. Next heat the oven to 425°F. Line a large rimmed baking tray with parchment rated for at least 425°F. Transfer the 8 chicken pieces onto the tray and spread them in a single layer. Leave about 1 inch between pieces where possible. Use your fingers or tongs to smooth any thick clumps of marinade across the meat. Don't pour leftover liquid from the bowl onto the tray. After the rest you'll notice the spice paste has settled into a more even coat. The pieces should look deep orange rather than wet and pale. Crowding the tray traps water and slows the browning. Spacing the meat lets hot air reach more of its surface.

Place the tray on the middle rack of the 425°F oven and roast for 12 minutes. Then use tongs to flip each piece and move the outer pieces closer to the center. Roast for another 8 to 12 minutes. Start checking the thickest piece with an instant-read thermometer near minute 20. You're looking for at least 165°F in the center. Don't rely on the dark spice coating as proof that the meat is safe to eat. If needed, keep roasting and check again every 2 minutes until the center reaches 165°F. The edges should turn deep golden brown while the thick parts stay plump and fully opaque inside. You'll smell toasted cumin and garlic. (I once packed the tray too tightly and the chicken released too much water. Giving each piece space made a big difference.) Stop at a safe internal temperature because extra oven time can dry the meat.

Take the tray out of the oven once every piece reaches at least 165°F. Let the 8 pieces rest for 5 minutes without cutting them. Meanwhile stir 1/2 cup plain whole milk Greek yogurt with 1 tablespoon fresh lemon juice, 1 small grated garlic clove and 1/4 teaspoon kosher salt. Mix for about 30 seconds until the sauce looks smooth. Next cut 1 English cucumber into thin rounds and slice 2 Roma tomatoes into wedges. Thinly slice 1/2 red onion and roughly chop 2 tablespoons fresh flat-leaf parsley. Keep the vegetables cool while you finish the chicken. After the rest slice each thigh piece across the grain into strips about 1/2 inch wide. The center should look fully opaque and moist while the cut edges stay slightly rough. Cut too soon and more juices escape onto the tray. A short rest helps the meat keep its moisture.

Warm 4 white wheat pita breads in a dry skillet over medium heat at about 325°F for 20 to 30 seconds per side. Turn each one once so both faces feel soft and warm. Don't leave the bread in the skillet until it becomes crisp because it'll crack when folded. Next spread about 1 tablespoon of garlic yogurt sauce inside each pita. Divide the sliced chicken evenly between the four breads. Then add the English cucumber rounds, Roma tomato wedges and red onion slices. Spoon the remaining yogurt sauce over the filling and scatter the chopped flat-leaf parsley on top. Fold each pita loosely around the filling so the chicken stays visible along the open edge. You'll see dark golden strips against the fresh vegetables and pale sauce. Serve right away because a long wait makes the bread soggy. Brief warming keeps the pita soft enough to fold without tearing.