Makes about 8 cups

Why This Recipe Works: We set out to create a deeply flavorful, nuanced beef broth that we could use in recipes or enjoy as a drinking broth. We started with the most important ingredient: the beef. Although many recipes call for roasting beef bones, we found that these broths didn’t have much beefy flavor. Using meat alone produced thin broths that lacked body. Finally, we settled on oxtails—they were economical, widely available, and served as all-in-one bundles of flavor-packed meat, fat, collagen-rich connective tissue, and bone marrow. Plus, since they’re sold precut, they didn’t require any special preparation at home. Next, we needed to figure out how to extract the most flavor from the oxtails. We browned them first to create fond, then simmered broths for 4, 8, 12, 24, and 48 hours. The range of colors and flavors amazed tasters; at 4 hours, the broth resembled chicken broth and had barely any beefy flavor, but by 48 hours, it had a burnt, metallic taste. Although the 12-hour broth had decent flavor, the 24-hour broth was the runaway winner: The beautiful mahogany color, rich beefy flavor, and luxurious, almost silky texture had tasters going back for seconds. An onion, a bit of tomato paste, and some bay leaves enhanced the broth’s meaty flavor while adding a touch of aromatic sweetness, and white mushrooms played a crucial role in rounding out the overall flavor with their warm, savory tones. We found that the long, slow simmer could be accomplished in a 200-degree oven or in a slow cooker set on low, keeping our recipe streamlined and hands-off.

Try to buy oxtails that are approximately 2 inches thick and 2 to 4 inches in diameter; they will yield more flavor for the broth. Oxtails can often be found in the freezer section of the grocery store; if using frozen oxtails, be sure to thaw them completely before using. If using a slow cooker, you will need one that holds 5 1/2 to 7 quarts. You can reserve the separated beef fat in step 4 and substitute it in savory recipes where olive oil, coconut oil, or ghee are called for.

2 tablespoons extra-virgin olive oil
6 pounds oxtails
1 large onion, chopped
8 ounces white mushrooms, trimmed and chopped
2 tablespoons tomato paste
10 cups water
3 bay leaves
Kosher salt and pepper

1. Heat 1 tablespoon oil in Dutch oven over medium-high heat until just smoking. Pat oxtails dry with paper towels. Brown half of oxtails, 7 to 10 minutes; transfer to large bowl. Repeat with remaining 1 tablespoon oil and remaining oxtails; transfer to bowl.

2. Add onion and mushrooms to fat left in pot and cook until softened and lightly browned, about 5 minutes. Stir in tomato paste and cook until fragrant, about 1 minute. Stir in 2 cups water, bay leaves, 1 teaspoon salt, and 1/4 teaspoon pepper, scraping up any browned bits.

3A. FOR THE OVEN: Adjust oven rack to middle position and heat oven to 200 degrees. Stir remaining 8 cups water into pot, then return browned oxtails and any accumulated juices to pot and bring to simmer. Fit large piece of aluminum foil over pot, pressing to seal, then cover tightly with lid. Transfer pot to oven and cook until broth is rich and flavorful, about 24 hours.

3B. FOR THE SLOW COOKER: Transfer browned oxtails and any accumulated juices and vegetable mixture to slow cooker. Stir in remaining 8 cups water. Cover and cook until broth is rich and flavorful, about 24 hours on low.

4. Remove oxtails, then strain broth through fine-mesh strainer into large container; discard solids. let broth settle for 5 to 10 minutes, then defat using wide, shallow spoon or fat separator. (Cooled broth can be refrigerated for up to 4 days or frozen for up to 1 month.)

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