Melt the salted butter in a large pan over a medium heat. Continue to cook for 3-4 mins until foaming and smelling nutty – when you stir it, the milk solids at the bottom should be golden brown. Remove from the heat and add the smoked paprika, ground cumin, salt and long-grain rice. Stir to coat. Pour over enough chicken stock to cover the rice by 2cm. Add the lemon peel. Bring to the boil over a high heat, cover, reduce the heat to the lowest setting and cook for 15 mins. Take off the heat. Leave to stand for 20 mins. Fluff using a fork, then spread out on a plate to cool. Will keep chilled in an airtight container for up to three days.