MAKE THE CHICKEN Combine the chicken, cinnamon sticks, fennel seeds, sage, bay leaves and allspice in a big pot. Add cold water to cover and season with salt. Bring to a boil and simmer for 45 minutes or until the chicken is fully cooked. Let the chicken cool completely in the broth.
Remove the chicken and strain the broth. Finely shred the chicken into a large bowl. Discard the skin and bones. Reserve the broth for later use. Add the parsley, cilantro and mashed potatoes to the chicken, season generously to taste with salt and mix well. Stir in the eggs. Form the mixture into patties about 2 inches round and 1/2-inch thick; the thinner the patties, the crisper they will be.
MAKE THE HARISSA SAUCE In a small bowl, whisk together all of the ingredients.
Heat oil in a large skillet. Fry the patties in batches until browned. Serve warm, with the harissa sauce on the side.