It's really rather simple, though the fish has to be just ready to spawn.  Here's how.  Carefully remove the roe and set aside in a cold place then finish cleaning the fish.  Place the roe in a fine-meshed sieve and let cold tap water run over it (and your hands) while you work.  Gently snip through the membrane encapsulating the roe with a sharp knife - if the fish and roe are ripe, it will snap free and collapse on itself like a sausage casing or a balloon popping.  Now, gently, strip the individual eggs from the connecting tissue - they're on it like bunches of grapes on stems.  Again, if the fish is ripe, they will come off easily.  Some will break, regardless.  The running water will carry the yolk away.  When done, continue to wash them thoroughly - until there's only a minimal level of foaminess in the water.  Transfer them to a cold non-metallic bowl, measuring them by volume.  Be precise - measure to the tablespoon of eggs.  Take good kosher salt and measure by volume 1 part salt for 32 parts eggs.  Grind the salt extremely fine - like powdered sugar - in a scrupulously clean and de-scented mortar and pestle.  Sprinkle over the eggs and fold in gently.  Let sit a few minutes, then transfer to a sterilized, then chilled, mason jar.  Exclude air from the top of the eggs - I use some plastic wrap weighted with dried peas - and close the lid.  Put it in the fridge where it will stay just above 32 deg. F.  Leave it alone at least a week.  It should be ready by then.

Since around here brookies and brownies come into season in late October - I can get caviar for Thanksgiving and it will be good through New Years (but, really, it should be eaten by then as it will go bad soon thereafter).  I have a friend with a trout farm who often has a surplus of roe after breeding next year's fish, so I can call ahead to make sure there will be some available when I show up.