*pseudo because I don’t really measure anything and always just sort of do this kind of thing on the fly.
This is what I did to make crab bisque. It was ridiculously tasty. I am not really into “subtle flavours”, so do know that this bisque is really crabby and just sort of hits you in the face with it’s overwhelming crabbiness. As you will see there isn’t much in it other than crab.
Boil some crabs. (I used two dungeness crab which in total came in just under four pounds). Save the water you boiled the crabs in. Some people like to salt the water but then it creates over-saltiness issues when reducing stock so I think you can get away without salting the water.
Take all the meat out of the crabs. Keep everything else (including the “goo”). You need the goo for the flavour in the stock. If you think the crab goo is disgusting then get over yourself and go eat something else.
It’s easiest if you just take the crab apart over a oven-safe pan. I used my pyrex lasagna pan. Throw the whole pile of stuff into the oven at 400 degrees for 10-12 minutes, or until you smell roasty crab smells. Then dump the whole pile back into the pot where the crab-water is. Boil it gently, with the lid on. The longer you boil it the tastier it will be. Add an onion and other veggies, if you want (I just did an onion). I boiled it for about 90 minutes. Stir it occasionally. Probably not a big deal if you don’t though. You may want to do this outside if this is an option for you (I have a burner on my BBQ) if you don’t want your house to smell like crab for days.
Once you run out of time and/or patience, fish out all the large chunks. Now boil it some more with the lid off to reduce the stock. For the stock for 2 crabs I added four glug glugs of Sherry. Then I reduced it by about 3 or 4x. (So, for each litre of crab stock, I reduced it down to a cup or a bit more).
Now you strain it all, first with a medium mesh strainer and then with a fine mesh strainer or a cheese cloth.
Make a roux by melting butter in a pan and then adding flour to the sizzling butter. People vary in how they like to do roux but there’s something called google you can use to figure that part out. I like it on the slightly browner side for colour but then it has less thickening power so adjust accordingly.
Then you dump crab stock in. Careful not to use too much as the stock may be salty. Make sure you stir rigorously as you add the stock to the roux.
Let it simmer a few minutes. Then add cream. You want it to be really kickass, use heavy (whipping) cream. You may be able to get away with using a lower fat cream or even milk, but note that the higher fat content leads to tastier/richer bisque and you don’t have the problem of curdling as easily.
You can warm up the crab meat a bit if you like, or in my case I just separated the meat into bowls and poured the hot bisque right on top. That resulted in perfect diving in temperature.
I would imagine this could work well for lobster too.