Quick fish stew

Name: Quick fish stew
Prep time: 10 min
Cook time: 30 min
Total time: 40 min
Cuisine: French
Ingredients: 3 tbsp garlic butter; 1 onion chopped; 2 x 400g cans plum tomatoes finely chopped; 1 tbsp balsamic vinegar; pinch of chilli flakes; 1 fish or vegetable stock cube; 2 roasted red peppers from a jar, sliced; 300g potato cut into chunks; 2 tbsp finely chopped parsley; 400g bag mixed seafood defrosted if frozen; 250g white fish or salmon chopped into chunks; 8 thin slices of baguette; green beans to serve (optional)