Cook the carrots, onion, thyme and garlic in some olive oil over a low heat.
Add the tomatoes and the fish stock.
Season with salt, pepper and a little sugar.
Cover the sauce with a cartouche made from baking paper.
Cook slowly for up to 2 hours. (At this stage, the burrida can be stored in the fridge for 48 hours.)
When you want to serve, reheat the sauce adding the fish and cook for about 5-10 minutes until all the fish is cooked.
Mix the softened butter with the garlic and parsley. Slice the baguette at an angle, grill on both sides and then spread on the parsley and garlic butter. Serve with the fish stew.