For the matzo tortillas: In a bowl, work the fine matzo meal, warm water, oil and salt very well together with your hands until a soft dough forms. Form twelve 1 1/2-inch balls, and roll between plastic wrap to form a tortilla shape.
Preheat a nonstick griddle or pan over medium heat. Cook the matzo tortillas on each side until lightly brown, flipping once.
For the brisket tacos: Set the oven for 325 degrees F. Sprinkle the brisket with cracked black pepper and kosher salt. Heat the oil in a Dutch oven over high heat. Place the brisket in the pot and sear on all sides, 2 to 3 minutes per side. When the meat is browned, remove from the pot and set the brisket aside. Reduce the heat under the pot.
To the Dutch oven, add the carrots, celery, onions and garlic, and let cook for about 5 minutes. Add the tomato puree, chipotle puree, cumin, oregano, thyme and bay leaf. Saute the ingredients together. Once the ingredients have cooked 2 to 3 minutes, add the beer and bring to a boil for 1 minute.
Return the brisket to the pot and pour in water until it covers the meat. Bring the liquid to a boil, and then lower the heat to a simmer. Cover with aluminum foil and place the pot in the oven until thoroughly cooked and tender, 2 to 3 hours. Remove from the oven. Let the meat rest and cool in the braising liquid.
Once cooled, remove the brisket from the liquid and cut into slices. Set aside.
Pour the braising liquid into a blender or food processor and blend until smooth. Then pour the braising liquid back into the pot and reheat over medium heat. Return the sliced meat to the pot and let it reheat in the sauce.
To assemble and serve: Serve 2 matzo tortillas per plate. Fill generously with the braised brisket. Then add 1 tablespoon tomatillo salsa, avocado and Horseradish Crema to top. Sprinkle with the cilantro leaves and serve.
Mix together the crema, horseradish, vinegar and salt.