This soup is quite quick to prepare, therefore you won't need a pressure or a slow cooker to make it, just a simple medium pot.
Wash, peel and grate the carrot and parsnip and dice the potatoes. Add them to the pot with the Low FODMAP Chicken stock, topping up with water to cover the vegetables. Bring it to the boil, then lower the heat and simmer for around 10 - 15 minutes, just until the vegetables start softening.
How much liquid I need to add when making a soup?
My rule is that when I cook as a soup, whenever it is with vegetables, fish or meat, I always add enough liquid to cover the content of the pot just above the ingredients level. Not below, because water will still evaporate and it will become too thick, also not too much over, because the soup will have less flavour. Of course, if you cook in a pressure cooker (not in this case), you will need to add liquid to the minimum level required for your specific pot.
Add all of the frozen fish and seafood to the soup, together with peas and finely chopped red chilli. There is no need to defrost the fish, it will thaw quickly in the stock and cook within around 15 - 20 minutes, depending on the thickness of your fish fillets.
When the vegetables, fish and seafood is cooked, season it with salt and black pepper. Add chopped spring onion. Squeeze the required amount of the tomato paste into a small bowl, add some stock from the soup, mix well and pour back in the soup. It will add flavour, colour and thickness to the soup. In the end, just garnish it with fresh parsley just before serving.