For the brisket: Bring the beef to room temp and pat dry. Sprinkle the brisket with salt and pepper. Heat 3 tablespoons of the oil over medium-high to high heat. Add the meat and brown on both sides, then remove. Add 1 tablespoon of the oil and then add the garlic, celery, carrots, chiles, onions and ginger. Season with salt and pepper, and stir 8 to 10 minutes. Add the tomato paste, and stir. Then, add the stock, tamari, mirin and vinegar. Add the brisket and cover. Braise in the oven until very tender, 2 1/2 to 3 hours.
Remove the brisket from the sauce. Puree the sauce to smooth in a food processor or with an immersion blender, if desired. Slice the brisket and add back to the sauce. Cool and store for a make-ahead meal. Reheat over medium heat, stirring gently.
For the rice: The night you serve, heat the stock and butter to a boil. Add the rice and stir. Season with salt and cover, reduce the heat to a simmer, medium low. In a food processor, pulse the spinach and cilantro into a fine chop. After the rice has cooked 15 minutes, stir in the cilantro, spinach and the lime zest. Cover and cook until the rice is tender, about 3 minutes. Fluff with a fork. Cut the zested lime into wedges.
Fill the bowls with the green rice and make a well in the center of the bowl. Fill with the beef, and top with the juice from a wedge of a lime, scallions, drizzle of sesame oil, sesame seeds and a few drops of hot sauce.