I make chicken stock all the time, but I recently found a few pounds of oxtails and also some beef bones, so I made a beef stock, which I have less experience with. I used pretty minimal other ingredients (a quartered onion, a head of garlic, some peppercorns, parsley stems, and a splash of fish sauce).
Although I did not brown the meat and bones, the resulting stock is actually pretty brown. It's already been strained through Chinois and resimmered/reduced to perhaps half of what it was originally in volume. When I taste it, it is really intense, like a somewhat too intense onion soup broth. I have added hardly any salt, apart from the fish sauce. If I were to use this for soup, I'd actually dilute it slightly and add salt. Is this to be used like a "demi-glace"?
So I'm wondering about things like this:
--What are some rules of thumb about how far to reduce beef stocks? Can any sound stock be reduced all the way to the "glace" stage?
--In the case of stocks that are significantly reduced, what rules of thumb guide how to employ them in later cooking? Is diluting the stock typical?
This stock, by the way, is seriously gelatinous when chilled.
Thanks for any thoughts!