1.Bring the stock to a gentle simmer in a medium saucepan.
2.Meanwhile, cut calamari hoods down the centre to open out. Score the inside in a diagonal pattern, then cut into pieces. Shell and devein prawns, leaving tails intact.
3.Heat half the oil in a large, heavy-based pan. Cook prawns and calamari over high heat, in batches, until the prawns have just changed colour. Remove from pan.
4.Heat remaining oil in the same large, heavy-based pan. Add onion and garlic. Cook, stirring, until onion has softened. Add rice and saffron, stirring to coat well with onion mixture. Cook, stirring for 1 minute. Add wine and simmer, uncovered, until liquid has evaporated. Stir in tomato puree. Cook, stirring, for 1 minute.
5.Stir in 1/2 cup of the hot stock. Cook, stirring, over a medium heat until the liquid is absorbed. Continue adding stock, 1/2 cup at a time, stirring between each addition, until all but 1/2 cup of the stock has been absorbed (this step should take about 20 minutes). Stir in remaining stock and mussels. Cover and cook for 5 minutes or until mussels have opened.
6.Return prawns and calamari to pan with the rind and parsley. Stir in gently.
Not suitable to freeze or microwave.Note