Scrub the mussels and pull out the beards. Discard any broken or open mussels. Rinse well and refrigerate. Peel and devein the prawns leaving the tails intact. Place the prawns in a bowl, cover and refrigerate. Put the stock in a heavy saucepan and bring to a boil. Reduce the heat to a simmer and cover. Heat the oil in a large saucepan over medium heat. Add the chopped onion, garlic and celery and cook for 2-3 minutes. Add 2 tablespoons of lukewarm water cover and cook for 5 minutes more or until the onions have been come soft. Add the rice and stir over medium heat for 3-4 minutes until the rice grains are well coated. Gradually add ½ cup of the hot stock to the rice, stirring constantly over low heat until all of the stock has been absorbed. Repeat, adding ½ cup of the stock at a time allowing each batch to absorb into the rice before adding the next. Cook and stir until the rice is tender, approximately 30-35 minutes.
Meanwhile, in a saucepan, bring ¼ cup of water to a boil. Add the mussels, cover and cook for 4-5 minutes, shaking the pan occasionally, until the mussels have opened. Drain and set aside, discard any unopened mussels.
Add the prawns, scallops, and remaining stock to the rice, stir well. Cook for 5-10 minutes over medium-low heat until the seafood is cooked and the rice is creamy and tender. Remove from heat and stir in the mussels and set aside for 5 minutes. Stir in the herbs and Parmesan and season to taste.
Seafood Recipes from Eastern Fisheries Include: