In a 6-quart slow cooker, combine the onions, chicken, lemon juice, olive oil, oregano, dill, salt, and pepper. Cover and cook on low for 4 to 6 hours, until chicken can be easily shredded with a fork. Before serving, taste and add more salt, pepper, fresh dill, or lemon juice as needed.
To make the sauce, whisk together the yogurt, lemon juice, salt, and pepper in a medium bowl. Sauce can be made ahead and kept, covered in the fridge, for up to 3 days.
To assemble the gyros, spread some of the lemon-yogurt sauce onto each piece of lavash or pita, add a few forkfuls of chicken, and top with chopped tomatoes, cucumber, onion, olives, and baby arugula. Squirt with more lemon juice if you like.
This recipe appeared in the Spring 2017 issue of Cape Cod HOME. It is from Sarah Waldman's new cookbook Feeding a Family.