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1
Preheat the oven to 425F.
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2
In a large roasting pan, combine the olive oil, shallots, and carrots and toss to coat.
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3
Add the beef bones and scraps and roast until browned and the vegetables are lightly caramelized, about 45 minutes, tossing once or twice for even browning.
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4
Transfer the beef and vegetables to a large soup pot along with the bouquet garni.
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5
Pour off the fat in the roasting pan and set the pan over a burner on medium heat until sizzling.
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6
Add the tomato paste and cook until lightly caramelized, about 1 minute.
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7
Add 2 cups of the water and cook, scraping up any browned bits stuck to the pan.
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8
Scrape the contents of the roasting pan into the soup pot along with the remaining water and mushroom trimmings, if using, and bring to a boil.
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9
Skim any scum that rises to the surface.
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10
Partially cover and simmer over low heat until the stock is flavorful and reduced slightly, about 3 hours.
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11
Strain the stock into a large, heatproof bowl, pressing hard on the solids to extract as much liquid as possible.
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12
Let cool, then refrigerate until chilled.
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13
Spoon the fat from the surface and, using a paper towel, blot any congealed fat from the surface.
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14
Will keep, tightly covered, in the refrigerator for up to 4 days or in the freezer for 3 months.
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15
I recommend freezing it in 2-cup containers.
