Clean the mussels with a soft brush or a bit of the green scrubbing cloth, removing the beard, any dirt and barnacles. Discard any open or damaged. Place in a bowl, cover with water and soak for an hour or two. Change water during process.
Rinse Clams in cold water, place in large bowl, sprinkle with the cooking salt, cover with water and soak for about 1 1/2 hours;
Discard water, rinse and drain clams.
Shell and devine the Prawns (Can leave tails intact).
Combine Wine and Saffron in a jug; leave to stand at least 30 minutes.
Prepare Chicken Stock, bring to boil and keep hot on cooker.
Heat oil in large pan, add chicken and cook on med/low heat until browned and tender;
Remove from pan, drain on kitchen paper and set aside;
Add chorizo to same pan and cook, stirring , until browned; Remove from pan, drain on kitchen absorbent paper and set aside;
Add butter to same pan, melt, lower heat, add onion and garlic and cook gently, stirring, for 5 minutes or so until soft;
Add rice, stirring constantly, for 2 minutes or so or until begins to pop;
Add peppers and wine mixture, stirring constantly to keep rice grains separate, until wine is absorbed;
Add chopped tomatoes,lemon juice, a ladleful stock and continue stirring frequently,until stock is almost absorbed;
Continue adding stock, stirring frequently, until absorbed for about 15/20 minutes or so until rice is almost tender;
Add mussels, prawns, clams, chorizo and green beans on top of rice mixture, cover,and simmer for some 5 minutes;
Add chicken, peas and scallops (if using) and continue to simmer covered another 10 minutes or so until clams and mussels have open and scallops are just cooked through;
Stand covered for 5 minutes or so, garnish with parsley, and serve, removing any unopened mussels and clam