Heat the oil in a large deep frying pan over a medium-high heat. Add the onion and a pinch of salt, then fry for about 5 minutes until starting to soften. Add the chorizo and fry for another 3-4 minutes. Add the rice and beans, stirring everything together.
Pour over the hot stock. Bring to a simmer and cook for 15 minutes. Turn the heat to medium-low, stir in the kale, then scatter over the prawns. Add the lemon juice, cover the pan with a lid (or a sheet of foil) and cook gently for 3-4 minutes.
Take the pan off the heat and let stand, covered, for 5 minutes. Serve with the lemon wedges alongside. Some garlic mayonnaise would go nicely, too.
