Easy bouillabaisse with Gruyère croùtes

Method

1. Empty the jar of sauce into a large saucepan, stir in the fish stock, hot, and the new potatoes, cut into bite-size pieces.
2. Bring to the boil, reduce the heat and simmer rapidly for 15 minutes, stirring occasionally, until the potatoes are just tender.
3. Meanwhile, preheat the grill to medium-high. When the potatoes are nearly tender, toast the baguette slices under the grill on 1 side. Divide the Gruyère, grated, between them and put under the grill for 1-2 minutes, until bubbling.
4. Cut 400g thick, skinless, sustainable cod or haddock fillets into bite-size chunks and stir into the soup. Simmer for 2 minutes, until just cooked.
5. Stir in a handful chopped fresh flatleaf parsley and season to taste. Divide between 4 bowls and serve each with 2 Gruyère croûtes for dunking.