Preheat the oven to 400 degrees F.
Marinate the chicken with piri piri seasoning. Dredge in the flour and pat off the excess. Heat a large skillet over medium heat and add 2 tablespoons of the oil. Add the chicken skin-side down and sauté until golden brown, about 5 minutes per side. Remove the chicken from the skillet and reserve.
Discard the oil and wipe the pan out with a paper towel. Add the remaining 1 tablespoon oil and heat over medium-low heat. Add the onion and cook until golden, about 10 to 12 minutes. Add the lemon zest, garlic and cook for 2 minutes more. Add the honey, lemon juice, and broth, increase the heat and bring to a simmer.2
Use a slotted spoon to transfer the onions to a 9- by 13-inch ovenproof casserole, and spread them out. Arrange the chicken, skin-side up in a single layer on the onions. Pour the cooking liquid over the chicken. Season with priri piri seasoning. Bake in the oven, basting every 15 minutes, until cooked through, about 45 minutes. Remove from the oven and serve.