Kalasoppa. A Finnish comfort food.

Purchase some cheap frozen fish. Any white fish will do, but black cod is both traditional and inexpensive. It's what your Mum used. Do not mess around with salmon or similar, as this will result in seljanka, which is both posher and more tasty.
Put some water to boil in a saucepan. Add coarsely chopped onion and coarsely chopped potatoes.
Curse the fact you forgot to buy fish stock, as the soup will now have even less of anything that resembles taste.
Add 10 - 15 black peppercorns.
Allow to boil so potatoes are nearly done.
Meanwhile, chop frozen fish into cubes. Add to soup.
Allow to boil so fish is done.
This won't take long.
Add milk so base becomes white. Reheat, but do not boil. Add salt if you want to.
Add knob of butter or margarine, depending which you have. Add dill (leaves&stems, not seeds).

Eat. Preferably with dark rye bread. Think about the times this was your favourite food of all, when you'd first eat your own bowlful (warm-brown bowls) and much, much later in the evening, sit on Daddy's knee and help yourself to his portion with your own spoon, long ago in early childhood when life was synonymous with happiness.