The good news is the Internet brings a world of knowledge to our fingertips. The bad news is it also brings a world of copypasta mistakes to our fingertips. This is why my last couple of batches of roasted beef bone broth failed.
The common mistakes in the recipes I studied are roasting the bones at too low a temperature, overcooking, and reducing the final broth. The bones must be roasted at high heat, 450°-500°, and you need a mix of nice meaty bones and bare marrow bones, not just nekked bones. Just bones; no veggies and no seasoning.
The other mistake is too much water to too few bones. You don’t need to reduce it if you use enough bones. Reducing is for when you don’t control flavor intensity, for example reducing a sauce made with wine to intensify the flavor. When you make broth you have complete control.
My method is to roast a mix of marrow bones and shanks, ribs, or oxtails. Roast ’em hot in a stainless steel roaster and keep ’em roasting until they are a beautiful dark brown. Turn them over a couple of times. It takes as long as 60 minutes to turn deep brown. I have read of roasting them long enough to scrape off and save the brown and then roast them some more for more scraping. Haven’t tried this yet.
Then dump them into a stock pot, and deglaze the roaster into the stock pot to capture all the good stuff. Add enough water to cover the bones. A pound of meaty bones per quart of water makes a lovely stock, and two pounds per quart makes a delectable rich broth. Naturally, you will vary this to suit your own taste. Simmer for 4-5 hours. Don’t add herbs, mirepoix, salt, pepper, nor garlic nor onions. Supposedly adding some vinegar releases more calcium from the bones, though this could be an old husband’s tale. I want a plain rich unseasoned stock or broth as a base for soups and stews, or to enjoy as a simple broth.
I put it in the refrigerator overnight so that the fat is easy to remove (or outside on cold winter nights) and then I have a wonderful rich multi-purpose broth.