Heat the oil in a large lidded saucepan capable of holding the shellfish then soften the shallots and garlic for a couple of minutes. Pour in stock and dry white wine and bring to a simmer before adding the clams and adding the lid.
After a few minutes tip in the mussels and replace the lid. It should only take a few minutes for all of the shells to steam open. Of course, if your clams and mussels are the same size put them in at the same time.
Heat the oil and butter in a large, lidded frying pan and gently fry the onion for a few minutes until transparent.
Add the garlic for a further minute then tip in the rice.
Stir the rice until it is all covered in the oil and then tip in some vegetable stock and a few strands of saffron before adding the lid.
Stir occasionally for about 10 minutes until cooked adding asparagus or green beans after 5 minutes.
Add cooked prawns to the rice along with some chopped Chorizo and extra white fish if liked. If the rice looks too dry add a couple of ladles of the shellfish liquor.
Pile all of the shellfish over the rice with a slotted spoon, scatter over some chopped parsley and serve with lemon wedges.