Salt and pepper the chicken on all sides.
Heat olive oil in a cast iron skillet until very hot, add the chicken, skin side down. Cook until skin has browned, turn over and brown on the other side. Remove from pan (chicken will not be cooked through).
Add the onions, cook until lightly browned, about 5 minutes.
Add the beer, scraping to deglaze the pan. Stir in 1/3 cup harissa and tomatoes. Add the chicken back in the pan, skin side up.
Roast at 400 for 15-20 minutes or until the chicken is cooked through.
Remove from oven, preheat the broiler.
Place pan under the broiler until skin has crisped, about 2 minutes.
Remove from oven, sprinkle with parsley prior to serving.