Preheat the oven to 400 degrees F. Place the chicken pieces in a large baking pan and pour the oil over them. In a small bowl, mix the salt, pepper, 7-spice seasoning, and cumin. Season the chicken pieces well with the mixture. Bake the chicken for 25 minutes.
Heat ¼ inch of olive oil in a frying pan over medium-high heat for a few minutes. Add a small potato slice and when it begins to sizzle, add batches in a single layer in the pan. Fry until they are crispy on both sides. Set aside the potatoes.
In a bowl, mix the minced garlic cloves, fresh lemon juice, and chicken broth for the sauce.
Once the chicken has cooked for 35 minutes, remove the pan from the oven and add the potatoes and the sauce. Top with the lemon slices, if using, and bake the chicken for another 30 minutes or until the temperature reaches 165 degrees F (as measured with a food thermometer).
Serve the dish warm, with the pita bread and garlic sauce on the side, if using.