I saw a similar dish to this on the menu at another restaurant in Spain, but as it's summer I thought the broad bean option seemed more appropriate. As the broad beans tend to end up being quite well-cooked in this dish it's perfectly acceptable to use frozen; in fact I find that frozen ones often yield better results.
1 lobster weighing about 600-700g
1 large onion, peeled and finely chopped
4 cloves of garlic, peeled and crushed
4tbsp olive oil
A good pinch of saffron
350-400ml fish stock
600-700g podded weight of broad beans
Salt and freshly ground black pepper
Pre-heat the oven to 200C/gas mark 6.
Bring a pan of salted water to the boil and plunge the lobster into the water. Bring to the boil and simmer for 5 minutes, then remove from the heat and leave to cool a little.
Gently cook the onion and garlic in 3tbsp of the olive oil for 2-3 minutes, then add the saffron, stock and broad beans and simmer for 2-3 minutes.
Meanwhile, remove the head from the lobster and give the claws a crack with the back of a heavy knife. Cut the body into 4 or 5 pieces through the shell into rounds.
Heat the remaining tablespoon of olive oil in a large frying pan that will fit in the oven, season the pieces of lobster tail and quickly sauté them on both sides for a minute or so until they have a golden colour. Add the head and pour in the broad bean mixture. Cover and cook in the oven for about 15 minutes.
The liquid should have more or less evaporated and formed a sauce coating the beans; if not, place it on the stove on a medium heat and cook for a further couple of minutes. Serve immediately.