In a large pot, pour in the 12 cups of water and add the tied parsley, onion, garlic cloves and potatoes.
Set the heat to high until the water is boiling, then lower to medium, cover and let the water simmer for about 10 minutes (the potatoes will be about half-way cooked).
Add the tomato paste, vinegar, salt and Conger eel (congro) and raise the heat to high until the water starts to boil.
Lower the heat to medium and let simmer covered for another 8 minutes or until the potatoes are just about cooked.
Uncover and add the remaining fish. Once again, raise the heat to high until the water starts to boil.
Lower the heat to medium, cover and let simmer for about 5 minutes. The fish and potatoes should all be fully cooked.
Move the fish and potatoes to a serving dish.
In a small to medium bowl, add all the sauce ingredients and mix well with a soup spoon or fork.
Pour sauce over the fish and potatoes. Leave some aside in case someone wants to add some to their soup.
Serve the fish and potatoes on a serving tray (with the sauce) and serve the broth in individual soup bowls with the bread cubes. Place lemon wedges, red wine vinegar and some of the fish sauce on the table as optional toppings for the soup.
