Preheat your broiler and place the oven rack to the highest position. Meanwhile season the brisket liberally with salt and pepper. Place on a wire set over a baking sheet and broil, turning once, until browned on both sides, about 12 minutes total. Once browned, transfer to a roasting pan. Add in any browned bits and add to brisket. Set aside. Turn the oven to 300ºF and place the rack to the middle.

Heat a large skillet over medium-high heat and add vegetable oil. Add the onion, carrots, celery and garlic and cook, stirring occasionally, until some of the vegetables are browned. This should take about 5-6 minutes. Add the Dr Pepper, ketchup, chili sauce and tomatoes, breaking the tomatoes with a wooden spoon. Simmer 5 minutes.

Pour the mixture over the brisket and add in the bay leaves, chili powder, cumin and oregano. Cover tightly with aluminum foil and roast until very tender, about 4 hours.

Transfer the brisket out of the braising liquid and let rest 30 minutes. Slice brisket against the grain and place back into braising liquid. Let sit 30 minutes and serve.