Preheat oven to 400 degrees F. Soak bones in cold, salted water (about 1 tbsp. per liter of water) for 15 minutes to draw out some of the blood and remove impurities. Drain, rinse and pat dry. Spread bones on a rimmed baking sheet.
Toss vegetables in oil and spread on a rimmed baking sheet.
Roast vegetables and bones in the oven until browned and aromatic, anywhere from 40 to 60 minutes. The vegetables sometimes take longer; if so, they can finish browning while you boil the bones and skim the scum.
Place bones in a large saucepan and cover with 6 quarts of cold water. Deglaze the baking sheet with a few tablespoons of red wine and add to the pot. Bring to the boil over high heat, and skim the frothy scum until it stops rising to the surface, about 10 minutes.
Turn down the heat to medium-low, add the browned vegetables, de-glazing the baking sheet as above, and add bay leaves, cloves, juniper berries and peppercorns.
Bring the stock to a slow simmer, uncovered. The bubbles should be large and slow and barely break the surface. More scum will probably rise to the surface; at this point I tend to ignore it — after a while it stays near the edges and can be skimmed off easily at the end. I never stir the stock, because that brings the scum back into the liquid and increases the likelihood of cloudiness.
Simmer uncovered for 4 hours. Strain through a colander lined with cheesecloth. Remove fat — either immediately with a fat separator, or by chilling overnight and skimming off the hardened fat next day.
When the fat is removed, pour stock into a clean saucepan and reduce by half over low heat.
Let cool to room temperature. Decant into storage container. One pint is a useful size to refrigerate or freeze.
Juniper berries are available at the spice counter at John Edwards Market on Main Street.