• In a small bowl, whisk all of the spices. Add the lemon juice and olive oil and whisk to combine completely.
• In a medium bowl, place about half of the chicken thighs and half of the marinade. Rub the chicken, coating each piece well all over with the marinade. Add the rest of the chicken and marinade and again rub each piece all over with the marinade. Cover and chill for one hour or up to one day.
• Make the tahini sauce by whisking the tahini, garlic, and salt. Set aside until the chicken is grilled. The sauce can be made a day or two ahead, covered and chilled. Bring to room temperature before serving.
• Heat the grill on medium high heat. While the grill heats up, thread the chicken and onion on skewers, disposing of any remaining marinade. Take care keep the chicken fairly loosely threaded so that more of it will char on the edges. I like stainless steel skewers. If using bamboo skewers, be sure to soak them in water first.

For Grilled Shawarma:

• Using a paper or other towel on grill tongs, coat the hot grill grates with oil. Grill the skewers with the top down on the grill for 8-10 minutes, or until charred on the edges and browned. Again coat another area of the grill grates with oil and turn the skewers, placing them on the oiled surface. Coat the top of the grilled skewer with olive oil, close the grill top and cook for another 8-10 minutes, or until charred on the edges and browned.
• Remove the skewers from the grill, and push the chicken and onions off onto a cutting board. Slice the chicken into 1/2-inch thick slices. Drizzle everything with more olive oil.
• Serve the chicken drizzled with tahini sauce, with extra sauce in a bowl on the side.

For Oven Roasted Shawarma:

• Heat the oven to 500°F with a rack positioned in the upper third of the oven. Line a sheet pan with parchment or non-stick foil.
• Placethe marinated chicken thighs and red onion slices evenly in a single layer onthe sheet pan, discarding the marinade. Roast for about 30 minutes, flipping the chicken halfway through cooking, until the chicken is crisped around the edges and golden brown. Turn on the broiler for a few minutes if needed.
• Slice the chicken into 1/2-inch thick slices. Drizzle everything with more olive oil.

For Stovetop Shawarma:

• Heat a tablespoon of extra virgin olive oil in a large skillet or grill pan on the stove over medium high heat.
• Remove the chicken thighs from the marinade and pat dry. Working in batches so the pan is not crowded with chicken (crowded chicken will steam rather than turn golden), Working in batches, sauté the thighs, turning them over after about 6 minutes and cooking for another 4 minutes or so. The chicken may release its own juices; pour these off if too wet in the pan.
• Once all of the chicken is cooked, wipe out the pan and heat again over medium high heat with a couple of tablespoons of extra virgin olive oil. Add the onions and sauté until some of the edges are slightly charred, but the onions are still firm, 3 minutes. Remove the onions from the pan to a platter and set them aside.
• Cut the sautéed chicken into ½ inch slices. Wipe out the pan, add two tablespoons extra virgin olive oil, and heat again over medium high heat. Working in batches so the pan is not over-crowded with chicken (crowded chicken will steam rather than turn golden), sauté the chicken pieces until the edges are golden and crisp in spots. Transfer to the platter with the onions and serve immediately.