Sauté the garlic, shallots and paprika in oil in a large shallow casserole with a tight-fitting lid; do not brown. Add the rice and sauté until it begins to color. Add the stock, salt and lemon zest; cover. Bring to a boil and reduce heat. Cook until the liquid is almost absorbed, about 15 minutes. Add the mussels, replace cover and cook another 5 minutes or until mussels open. Garnish with chopped parsley.