On a rainy cold day, a hot bowl of Irish seafood chowder is perfect. I adjust the ingredients according to what is fresh at the market. Today I found good, wild-caught salmon and cod, but no fresh clams or mussels. They did have nice wild-caught shrimp and scallops, however. I prefer to use leeks, but they were $5 a bunch, and that just hit me in the cheapskate bone, so I am using yellow onions instead. I love seafood chowder, but I prefer it with a less fishy overall taste, so I am using my homemade vegetable broth instead of fish stock or clam juice. 

All of which is to say: Don’t marry yourself to one recipe, but be flexible according to what looks good at the market, and what your personal tastes are. Here is the recipe I use - obviously, I adjust this as I go each time. 

About a quart of veg broth, chicken stock, or fish stock (it is well worth your time to make this yourself. Storebought is full of preservatives and tastes like it. Stock is easy to make and the base for your soup, so its quality really matters.)

A few leeks or one yellow onion, diced 
Two carrots, diced
Two stalks of celery, diced 
3 red potatoes, peeled and diced
Pancetta or bacon 
Pint of organic heavy cream 
Dried thyme leaves 
Fish and/or shellfish. Fish should be chopped in to bite size pieces; shellfish must be rinsed very thoroughly to remove all sand
Sea salt and pepper 
Dry white wine 
Fresh parsley, chopped

Put a little olive oil and the chopped bacon or pancetta in a large pot. Cook the bacon over medium flame for a few minutes, then add the onions, salt, pepper, and thyme. Add olive oil as necessary to make sure the onions don’t burn, you shouldn’t need more than a TBSP. Once the onions start to become translucent, toss in a couple of spoons of flour. You want to coat the onions in flour so that there is no dry flour left, just a bit of a paste. This will thicken the soup. 
Then add your broth, plus the celery, carrots, and potatoes. I like to add a little dry white wine at this point too. Let this mixture cook until the veg are soft, then taste to see how you need to adjust the seasoning. 
Now add the cream and let it heat up, taste again to adjust seasoning. If you find you want a thicker soup, don’t just put flour in the pot, it will clump. Take some of the broth and put it in a little bowl, just a tablespoon or so. Add flour to make a paste, and gradually add liquid until it’s the consistency of pancake batter. You can add this to the soup with no fear of clumping, Just be careful to add a little at a time! 
Once the soup is hot, you can add the fish. It will only take a few minutes for it to cook. Put the soup in bowls, top with the parsley, and serve with brown bread.