You need 1 ingredient. The key ingredients include: ["Ingredients", "5 pounds flat-cut beef brisket (see Note), trimmed", "2 tablespoons extra-virgin olive oil, divided", "4 large onions, thinly sliced", "6 cloves garlic, minced", "1 teaspoon dried thyme", "1 teaspoon coarsely ground pepper", "1 6-ounce can tomato paste", "2 cups reduced-sodium beef broth", "1 teaspoon salt", "2 tablespoons butter, softened", "2 tablespoons all-purpose flour", "1 tablespoon Worcestershire sauce", "Tips & Notes", "Make Ahead Tip: Prepare onion mixture (Step 2) using 2 tablespoons oil (instead of 1) to cook the onions. Cover and refrigerate for up to 2 days. To finish, complete Step 1, bring the onion mixture to a simmer and finish with Steps 3-5. The cooked brisket and gravy can be refrigerated for up to 3 days. | Equipment: Large (5- to 6-quart) slow cooker", " Timing Tip: Cook the brisket for the shorter amount of time suggested if you prefer firmer, sliceable meat. If you like it to be falling apart, for shredding rather than slicing, set your timer for the longer time.", " Note: Brisket cuts are notoriously fatty, but the flat ""first-cut"" is much leaner than the fattier ""point cut."" It may be worth calling ahead to make sure your supermarket or butcher has one on hand."].