1. Peel and chop the onions. Peel and chop the garlic. Peel and dice the potatoes. Cut up the parsley.
2. In the casserole dish, heat up the oil and brown the onions. Add the water, the stock, the turmeric, the tomato puree and half the chopped garlic. Salt lightly, as the stock is already seasoned, and pepper. Bring to the boil, then add the pieces of fish.
3. Place the potatoes in the steam basket, sprinkle them with the rest of the garlic and the parsley.
4. Place the steam basket on the casserole dish, cover and simmer for 40 minutes from boiling point.