In a large frying pan or paella pan, heat a generous amount of olive oil (enough to cover the bottom of the pan) over medium heat. Add the beans and the garlic. Add the squid and continue to cook gently.
Grate the tomato directly into the pan (or grate onto a plate and add to the pan). Add the eight smaller prawns and continue to cook for 5 to 10 minutes. Add salt to taste, cook for 2 minutes, then remove from heat and set aside.
Meanwhile, heat a small to medium saucepan over medium high heat till very hot. Add the mussels to the hot, dry saucepan, and cook until the mussels have opened. Remove the mussels from the pan and reserve. Repeat this process with the clams, ensuring you save the clam juice that collects in the pan. Set the mussels and clams aside.
Bring the frying pan back to the heat and heat the mixture over medium heat till simmering. Stir in the paprika, then add the rice (do not rinse the rice before using!). Cover with the fish stock. Sprinkle in the saffron and gently stir in, without disturbing the rice. Lay the crayfish and king prawns in the pan, then add the mussels, clams and clam juice. (It looks nicest if you arrange the seafood in an alternating fashion in the pan.)
Cook the paella over low heat until the rice is soft. Resist the urge to stir! The rice will slowly absorb most of the fish stock, but should not get overcooked and gooey.
When the rice is tender, remove the pan from the heat and cover with a clean teatowel. Let the paella rest for 20 minutes until all of the liquid is absorbed.
Serve the paella straightaway with lemon wedges. Enjoy!