Some of these stocks include scraps of vegetables, and sometimes they're all about the meat. I figure that I can add the vegetable flavor later, if that's what I want. Yeah, maybe that's not traditional, but some days there aren't any scraps of vegetables hanging around.
And I never add salt and almost never add any herbs. I don't always know what I'm going to do with the stock, so for me it's better to leave it unsalted and unflavored so I can season it properly with it later. The exception is when I've got a roast that is highly flavored. The flavoring ends up in the stock and when I store it, I label it accordingly so I'm not surprised when I use it later.
Much of the time, the stock is made for later use rather than an immediate soup. If we've just eaten chicken, I might want to have something else when we've finished with chicken roast chicken and all its leftovers, rather than moving right on to chicken soup. So I make the stock and freeze it. But before I freeze, I reduce. A LOT.
While some of my stored stock ends up in gravy or as a base for something else, the majority of it ends up in soup. To me, the key to a flavorful soup is a good base, whether it's a vegetable base or a meat base. I've had soups that were little more than vegetables served in the water they were cooked in. The liquid in a soup should be flavorful, it shouldn't just be hot water that the solid bits are swimming in.
So, to make the soup flavorful and to save on storage space, I reduce the stock. I know some folks who think it's a great idea to end up with gallons of stock from one scrawny chicken carcass, but that doesn't make a very flavorful stock. And if you're planning on freezing it, you're taking up a lot of space for water that doesn't need to be there. If it's too thick or too flavorful, you can add water to it when you use it. But really, when was the last time you ate soup and thought, "gee, there's too much flavor in this soup"?
But how far can you reduce a stock? I might reduce a stock until there's just a half-inch or quarter-inch of liquid at the bottom of the pot if I haven't started with a lot of bones. In some cases, that liquid is thick - almost syrupy. How much I reduce depends on how thin the liquid was to begin with, how much time I have for simmering, and how much freezer space I have.
This last time, I reduced my soup to about a quart of liquid. After I chilled it, I cut it into four slices with a knife - I figure that one of those will be plenty for whatever I'm going to make with it.
It's pretty darned solid.
The steps to making stock are pretty simple. Start with whatever bones you have left from chicken, beef, pork ... If you've got a crockpot, it's ideal for making stock, but you can also use a stockpot, Dutch oven, or any pot big enough to hold the bones and liquid. Put the bones in, add cold water to cover, cover the pot, and set it on low. The key here is that you want to cook the bones slowly. A bare simmer. You don't want to boil the heck out of it.
I typically start the process after dinner and let it go all night. In the morning, I check it to see if it looks like I've extracted enough flavor. Basically, I want whatever meat that was on the bones to be very soft and just about flavorless. If there were joints in the bones, they should all be loose and falling apart.
There have been times I've left it simmering until that evening. It depends on what the meat was.
I let the liquid cool until I can handle it, then I strain all the bones and meat and bits out. Then I put the liquid into a container and stash it in the fridge to chill.
The next day, the fat will have risen to the top and solidified. I take that off. Some fats are worth saving - like duck fat. Some aren't worth keeping. Sometimes there's a layer of scum at the top, just under the fat. I skim that off, too. (Yes, you typically skim the scum while you're cooking, but if I chuck everything into the crockpot at night, I tend to ignore it until it's done cooking. I haven't seen any ill effects from doing this, but feel free to skim while it's cooking, if you prefer.)
Sometimes there's a layer of sediment at the bottom that I discard, as well. Or, I might leave that be and strain the stock again later, though a finer strainer or through cheesecloth.
After I've peeled off the fat and skimmed the scum, it goes into a pot on the stove. At this point, it's pretty likely that my stock is already jelly-like when chilled. I let the stock simmer to reduce it - I usually reduce it to about 1/4 of its original volume, and sometimes I continue reducing until it's even less. Then I strain it again, if needed, and put it into a container to chill again. Then when it's cold, I portion it if I think I'm not going to use it all at once, and the I freeze it.
While it takes a long time to make the stock, it's pretty much unattended. The crockpot doesn't need your attention at all, and most of the simmering can be done without much intervention. Just make sure you don't let it boil out completely and burn the bottom of your pot.