With the rack in the middle position, preheat the oven to 200 °C (400 °F).
In a pan of salted boiling water, cook the potatoes and carrots. Drain and set aside.
In another pan, brown the onion and bacon in the oil. Add the bell pepper, corn, and garlic and sauté until tender. Season with salt and pepper. Sprinkle with the flour and cook for 1 minute, stirring constantly. Add the milk and bring to a boil, stirring with a whisk. Adjust the seasoning. Add the potatoes, carrots, fish, parsley, and lemon juice. Pour into a 2 litres (8 cups) soufflé dish. Set aside.
In a bowl, combine the ingredients. Set aside.
Roll out the dough so that the diameter is about 4-cm (1 ½-inch) larger than the soufflé dish. Moisten the dough. Cover the dish with the dough, moistened side down, and press on the sides for the dough to adhere to the dish. Lightly brush the dough with the egg wash and make a hole in the middle. Bake for about 45 minutes or until the pastry is golden brown.
You can also make the haddock pot pie into individual portions in six 375 ml (1 1/2 cups) ramekins. However, you will need a bit more puff pastry, approximately 300 g instead of 200 g.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.