Heat oil in a four-quart casserole or saucepan. Add onion and lamb or chicken and cook, stirring frequently, until just beginning to brown, about 5 minutes. Add tomatoes, tomato paste, paprika, cayenne or harissa, saffron and salt and pepper. Stir, then add 8 cups water. Bring to a simmer and cook for 45 minutes.
Add orzo and chickpeas and cook 15 minutes, until orzo is tender. Add cilantro and parsley. Taste and adjust salt and cayenne or harissa. Add dried mint. Cook for 5 minutes, then serve.