1. In a 6- to 8-quart Dutch oven or soup pot, heat 1 teaspoon of the oil over medium-high heat. Season chicken with salt and pepper, add to the pot and brown on all sides, 6 to 8 minutes. Remove the chicken from the pan and set aside.
2. Wipe any fat from the pot. Add the remaining 1 teaspoon oil and onions and cook, stirring, until softened, about 5 minutes. If necessary, add 1 to 2 tablespoons of water to prevent scorching. Add cumin, saffron and cinnamon sticks; cook, stirring, until fragrant, about 30 seconds. Stir in sweet potatoes, tomatoes, chickpeas, orange juice and honey; bring to a simmer.
3. Return the chicken pieces to the pot, pressing them down into the vegetables. Return to a simmer, reduce the heat to medium-low, cover and simmer, stirring occasionally for 30 minutes. Add prunes and continue to simmer until the chicken is very tender, about 10 minutes more. Season with salt, pepper and harissa to taste.