Foodie Friday Returns: Fishy Realness Edition

So I've preciously confessed that my favorite recipe of all time may be poule au pot, the humblest of boiled chickens, one of the classic born-of-poverty preparations that sits at the base of all good cooking, the sort of dish that, if you do it right, will taste better than anything you'll ever eat in a restaurant, anywhere, ever.  Now another recipe I really like is this simple fish soup, thickened with a roux, a rip-off of the sort of thing you find in Brittany or along the coast of Poitou, although over there you'd probably actually dry and mill the fish bones . . . I'm a little too lazy for that.  The recipe calls for a few strands of saffron, which will make it prettier and more aromatic, but which can be dispensed with if you're really into eating like a peasant.  I like to use mackerel, which is nice and oily with a firm flesh--also cheap--but almost any light-fleshed fish will do.  Do not under any circumstances use salmon.  You'll need a blender or an immersion blender or a rough-and-tumble food mill and a very fine sieve.

a 2-3-lb fish (I use a mid-sized mackerel)
1 yellow onion, diced
1 whole head of garlic, smashed
a couple of carrots, peeled, chopped
some fennel fronds, chopped (if you've got 'em)
a few tomatoes, peeled and hand-crushed (good canned ones are fine)
butter
flour
sea salt
black pepper
a few saffron strands


Fillet the fish and remove the skin from the fillets.  Set the meat aside; keep the skin for the stock.  Chop the carcass into manageable pieces.

In a deep stockpot, melt a generous several tablespoons of butter.  Add the onion, garlic, and carrots with a pinch of salt and sauté until soft.  Add the fish parts and skin and sauté for a few more minutes.  Add the fennel and tomatoes and stir together.  Fill the pot with water.  Crush the saffron between your fingers and add it as well.  Bring to a boil, and then reduce heat and simmer low for 30-40 minutes.

Take the stock off the heat and blend everything together.  It will turn an ugly, almost-brownish color, but don't worry.  Strain it through the fine sieve into a bowl, working back and forth with a spatula or wooden spoon to squeeze all of the liquid out.  Discard the solids.  The stock that remains will have a vibrant, red-orange color.

Wipe out your pot and put it back on the stove.  Melt more butter.  Add a bit more salt.  Add a tablespoon or two of flour, whisking together to form the roux.  When it is smooth and begins to darken, becoming almost sandy in color and texture, slowly add in the stock, whisking as you go.  When all the stock has been added, let it simmer quickly for a few minutes.  Chop up the reserved fish, season with salt and pepper, and add to the stock to cook in it.

Serve immediately, hot, with thick, toasted bread.