Preheat the oven to 400°. Pat the chicken dry. Combine the salt, cumin, paprika, pepper, and allspice. Rub the spice mixture evenly onto the thighs, on both sides.
Heat the oil in a very large, deep, ovenproof skillet over medium-high heat. Add the chicken thighs, and brown on both sides, about 5 minutes per side, then transfer them to a paper towel lined surface. Do this in batches if necessary.
Pour off all but 2 tablespoons of the fat left in the pan, reduce the heat to medium-low, and add the onions. Cook, stirring frequently, for about 20 minutes until they are very soft and browned, but do not allow them to get too dark; adjust the heat as necessary. You can add a tablespoon of water from time to time as you go if they appear to be getting too brown.
Stir in the broth, olives, hot sauce and lemon wedges. Return all of the chicken to the pan, skin side up, nestling the pieces into the sauce. Cover the pan and place in the oven and bake for about 30 minutes. Remove the lid and bake for another 15 minutes, until the chicken is cooked and tender and the skin is crisped.
You can transfer everything to a serving dish, or just serve directly from the pan. Sprinkle with the parsley before serving.