Step 1

Heat your oven to 375F.

Step 2

Spread the bones in an even layer on a sturdy baking sheet and roast for 90 minutes. Make sure your baking sheet has sides at least 3/4" high as the bones will throw a lot of fat.

Step 3

Remove fat and sprinkle the carrots, onions, shallots and leeks overtop. Roast another 30 minutes or so.

Step 4

Place bones and aromatics in a large stock pot, add the tomato paste and thyme and simmer gently (I mean gently) for around 18-24 hours.

Step 5

Remove from heat. Let cool slightly, remove bones and strain through a fine strainer.

Step 6

Let cool completely. Skim any surface fat.

Step 7

Return to a pot and simmer gently to a final volume of 2-3 cups.

Step 8

Portion demi-glace in an ice cube tray and freeze. Place cubes in a zip loc bag or better yet vacuum pack 3 or 4 cubes per package.

Step 9

Use on your unsuspecting guests to amaze them.