Preheat oven to 450 degrees. Place veggies in roasting pan, drizzle with olive oil and season with salt and pepper. Place brisket on top of veggies, fat side up. Spread spice mixture over roast. Bake uncovered for 30 min.
Lower temp to 350 degrees. Pour sauce over meat. Cover tightly with foil. Bake for 2 ½ -3 hours. Allow to cool overnight in the fridge.
Separate meat from sauce and veggies, and slice while cold. Strain the sauce of floated congealed fat. Using an immersion blender or blender, blend the sauce and veggies together until smooth. Return sliced meat to pan and pour sauce over the meat. Cook at 350 for an additional 30 minutes.