Preheat the oven to 375°F (190°C).
In a food processor, combine the wet ingredients and process for 90 seconds until smooth.
Add the dry ingredients to the processor and continue blending for 2 full minutes (I know this sounds like overkill) until a very stringy dough forms
Let the dough relax for 5-10 minute and then shape it into a compact loaf.
In a bowl, mix together the stock, wine, vinegar, brown sugar and tamari to form your braising liquid.
In a large casserole dish, arrange the onion, potatoes, carrots, and halved garlic heads around the edges, leaving space in the center for the brisket.
Place the loaf in the center. Pour the braising liquid evenly over the vegetables and brisket. Drizzle the olive oil over the top. Cover the dish tightly with a lid or foil.
Transfer the casserole to the oven and roast for 40 minutes.
Remove the cover, use tongs to carefully flip the brisket over, spoon the braising liquid over the brisket and vegetables, and return the dish to the oven uncovered. Continue roasting, basting every 10 minutes, until the vegetables are tender and the brisket is firm, 50-60 minutes longer, until 90% of the liquid has evaporated or been absorbed.
Remove from the oven and allow the brisket to rest for 10 minutes before slicing. Serve with the roasted vegetables and a drizzle of the reduced braising liquid, garnished with parsley and chives.