Toast pistachios in a dry small skillet over medium-high heat, stirring often, until golden brown, about 5 minutes; let cool.
Combine 1/4 cup vinegar, 1/2 teaspoon paprika, and a pinch of kosher salt in a large saucepan and add water so mixture comes 1" up sides of pan. Fit with a steamer basket and bring liquid to a simmer over medium. Add beets, cover pan, and steam until tender, 30-40 minutes. Transfer to a large bowl and let cool slightly.
While beets are still warm, add 2 ounces goat cheese, remaining 1 tablespoon vinegar, and remaining 1/4 teaspoon paprika; season with kosher salt and pepper. Coarsely smash beets with a fork or potato masher, leaving some bigger pieces.
Serve topped with nigella seeds, pistachios, sea salt, and remaining goat cheese and drizzled with oil.
Heat a large skillet over medium high heat and sauté onions in vegetable oil, stirring occasionally, until caramelized and most of liquid has evaporated, about 15 minutes. Add halved garlic cloves and saute for 3 minutes more. Stir in spices and seasoning (paprika, salt, garlic and onion powders, black pepper, cayenne, oregano and thyme) and cook for 2 minutes. Set aside.
In a large bowl, stir together the beef stock, ketchup, chili sauce and brown sugar.
Cook the Brisket
Lightly grease crockpot. Place brisket in a crockpot (I had to cut my brisket cut in half and stack it to get it to fit), spread onion mixture over the top, then pour sauce mixture over the entire dish. Cover with the lid and cook it on LOW for 10 hours. (I did this overnight.) Do your best to lift the lid up as little as possible, though if you have a section of the meat sticking out of the sauce, rotate it under the sauce for at least a few hours of the cooking time.)
Rest the Brisket
When the brisket is cooked but still hot, use a spoon to scrape off any large fat deposits adhered to the top and bottom of the brisket. (This part is easiest to do when hot. The sauce will be de-fatted after it has chilled.)
Transfer the brisket and all of its sauce to a baking dish. Chill entire dish in the fridge for several hours and up to one day; this resting time will significantly enhance the flavor and texture of the meat (don't be tempted to skip this step; just do it!)
An hour before you’re ready to serve it
Preheat your oven to 300°F, and remove the dish from the fridge. Remove all of the fat that has solidified on top with a slotted spoon for a less oily finish.
Carefully remove the meat from its sauce and place on a large cutting board. Cut the brisket into 1/2-inch slices.
(Optional: you could run your sauce through a food processor for a smoother sauce; I didn't.)
Carefully place the sliced meat (moving it in large sections with a spatula helps keep it together) back into the sauce and spoon the sauce over the meat. Replace the lid or cover the dish tightly with foil and reheat in the oven until it is bubbling at the edges — this usually takes up to to 30 minutes.
