Heat the oil in a large saucepan, add leek and onion and cook for 2 minutes or until starting to soften. Add garlic, capsicum and fennel and cook for a further 5 minutes or until softened.
Add wine, stock and tomatoes, then season with pepper to taste. Simmer for 30 minutes or until the mixture has thickened slightly. Stir in tomato paste, herbs de Provence and zucchini, then continue simmering for 10 minutes, adding a little water if the mixture becomes too thick.
Meanwhile, to make the polenta: in a medium-sized saucepan, bring stock and water to the boil. Slowly add polenta, stirring constantly. Reduce the heat to low. Keep stirring for 2 minutes, until thickened. Remove from the heat. Season with pepper. Cover to keep warm.
Stir fish and shellfish into the tomato mixture. Cover and simmer gently over medium heat for about 5 minutes or until all the seafood is just cooked. Add parsley, peas and spinach and stir through until spinach has wilted.
Serve fish stew in bowls over polenta mash.
Italian clam stew with asparagus Use 3 onions, chopped, and omit the leek. In Step 2, omit the stock. Replace the seafood with 1 kg clams in their shells. Add them to the mixture, cover and bring to the boil, then simmer over a low heat for about 2 minutes. Add 1 bunch asparagus spears, cut into bite-sized pieces, cover and cook for 5 minutes or until all the clams have opened (discard any that remain shut) and the asparagus is just tender. Serve with the polenta mash.
If your supermarket doesn't stock dried herbes de Provence, use a mixture of dried thyme and rosemary. * You can substitute celery for the fennel. Use 2 stalks and add in Step 1 with a pinch of crushed fennel seeds.