Here's the recipe I use. It's a combination of a couple of different ones.

Maxine’s Spicy Beef Brisket

INGREDIENTS
1 4–5 lb. brisket, trimmed of excess fat
2 large onions, diced
2 cloves garlic, minced
1 tsp salt
4 tablespoons butter unsalted or olive oil
¾ Pound pitted prunes chopped
½ Cup Raisins
2 T grated Ginger
1 14-oz. bottle Heinz ketchup
1 heaping Tbsp. brown sugar
1-½ Tbsp Worcestershire sauce
¼ cup Dijon mustard
1 T tomato paste
1 Tbsp. dry mustard
1 tsp Ground Coriander
1 tsp Ground Cumin
3 Tbsp. vinegar (not balsamic)
½ tsp. chili powder
½ tsp. paprika
½ tsp. salt
2 bay leaves, placed on top of meat
1 cup Beef Broth

PREPARATION
1. Preheat oven to 325°.
2. In a large cast iron skillet melt the butter on medium heat and add in the onions and half the salt.
3. Let cook for 15-20 minutes stirring every few minutes.
4. Once they start caramelizing remove them from the pan.
5. Season the meat with salt and pepper and brown in a heavy-bottomed frypan. Transfer to a large Dutch oven, Roaster or Pyrex glass roasting dish.
6. Combine all the sauce ingredients in a large bowl and pour the sauce under and over the browned meat in the roasting pan. Top with the caramelized onions raisins and prunes. Roast for at least 3 hours, covered. Baste halfway through the baking time.
7. Cool slightly before slicing. Or, if making ahead, slice and wrap in plastic and then foil, and freeze or refrigerate (store sauce separately). Reheat in a 300° oven with sauce liberally spooned over the sliced meat.

Whichever brisket recipe you opt for, just remember a couple of things:
• Salt it well all over. It’s hefty cut of meat; it can take it.
• Brown it well all over before you braise it.
• Better to cook it a bit too long than too short. No one wants tough meat.
• When the brisket is done cooking (pierce it with a knife; it should give easily), I like to remove the meat from the sauce to let it cool. You can do this a few days ahead, even. I then strain the solids from the sauce, and after the gravy cools in the fridge, I skim the solidified fat cap.
• Now, the important part: Slice the cooled meat against the grain, and layer it into a baking dish and then pour the sauce all over it.
• Cover and slowly reheat at, like, 300°. Do this, and each slice will absorb the sweet, silky sauce—and become that much more tender—while doing so.