3/4 cup vegetable oil
1 large Spanish onion, minced
5 cloves garlic, minced
1 teaspoon crushed-red-pepper flakes
1 tablespoon tomato paste
7 tablespoons light brown sugar
5 cups brewed coffee
1/2 cup cider vinegar
1 (128 ounce) can peeled, chopped tomatoes
Kosher salt and freshly ground black pepper
1 (4 pound) brisket
In a medium pot, heat 1/4 cup of the oil over medium heat. Add the onion and cook, stirring, until soft and golden brown, about 7 minutes.
Add the garlic and cook, stirring, until fragrant, about 30 seconds. Stir in the red pepper. Add the tomato paste and cook, stirring frequently, about 1 minute. Stir in the brown sugar. Pour in the coffee, vinegar, and tomatoes; bring to a boil; and then lower to a simmer. Simmer 10 minutes. Set aside to cool.
Working in small batches, transfer the tomato-coffee mixture to a blender and puree. Season with salt and pepper to taste. Set aside.
Preheat the oven to 275 degrees F.
Season the brisket with salt and pepper. In a Dutch oven with a tight-fitting lid, heat the remaining 1/2 cup oil. Brown the brisket on both sides. Drain off the oil, leaving the brisket in the Dutch oven. Turn the brisket so that the fat side is facing up and then coat it with the pureed tomato-coffee mixture. Cover the Dutch oven and place it in the oven. Bake for 3 hours, basting frequently.
Remove the lid and bake uncovered until the brisket is glazed and very tender, about an hour and a half more. Remove the brisket and set it aside to rest for 10 minutes, covered with foil, before slicing thinly across the grain.