Preheat oven to 450 degrees. Lay veal bones in a large roasting pan. Drizzle with olive oil and season with salt and pepper. Ideally the bones would be in a single layer but that is tough to do with this many bones. Roast bones for 1 hour stirring 1-2 times to ensure even browning. After 1 hour reduce the oven temperature to 375, smear the tomato paste over the bones, add the vegetables and roast for 1 hour more. Stir 1-2 times. (do not add water at this time)

Remove roasting pan from the oven to stove top over medium heat for a couple of minutes. Transfer the bones, vegetables to a large stock pot. Use 1 cup of wine to deglaze the bottom of the roasting pan. Then add the deglazed liquid and the other 15 cups of water to the stock pot. Add the bay leaves, peppercorns and parsley at this time. Simmer for approximately 8 hours. During the first hour or so skim off any froth that rises to the top. (Note: I remove the bones and solids to the lid of my roasting pan, deglaze the bottom of the roasting pan. Then I put the solids and the 15 cups of water back into the bottom roasting pan. I simmer in the roasting pan gently over 2 burners for the next 8 hours stirring occasionally. I put the lid on loosely since the roasting pan surface is larger than the stock pot. If the liquid goes below the level of the bones top it up. I check it at the 4 hour stage and adjust if necessary. I don't like to add water more than half way through the simmer period.)

Pour the stock in batches through a sieve, discarding all the solids. This is the point I put the stock in my freezing garage, covered overnight so I can chip off any fat that congeals on the surface the next morning. Alternatively you can skim off any fat while it is still warm and go on to the next steps.

Once fat has been removed, continue to gently simmer the stock about another hour. At this point you may have only about 4-6 cups. (I just go with whatever quantity is left at this point.) Remove from heat and cool uncovered about an hour.

Stock will keep about 1 week in the fridge well sealed or 3 months frozen. You can freeze it in ice cube trays and then seal if you want to add a cube or two to various pan sauces. I use 2 cup containers to freeze it in.

At this point you have veal stock. You can use it in recipes that call for veal stock or eventually season and reduce it further to demi-glace.