This recipe is a natural for a slow cooker but you have to start 7 days ahead of time to fully brine the brisket. To cling to some tradition we are going to finish it with potatoes and Brussels sprouts leaves. The dill fronds and the miso give it a really fresh finish.
Place the cold water and the apple juice in a large pot and bring to a boil. Add the maple syrup, Instacure, mustard seed, allspice, bay leaves and salt. Cook for three minutes at a rapid boil and then turn off the heat. Add the ice and wait for the brine to lower to room temperature.
Place the brisket in a large tub and cover with the brine. Cover and place in the refrigerator.
After one week, pull the brisket out of the brine and then strain the brine. Save the spices and bay and discard the liquid.
In an All-Clad frypan, warm the olive oil over medium high heat. Add the onions to the pan and cook for fifteen minutes, turning once in a while, until well browned and a touch charred. Set aside.
Set up the All-Clad slow cooker and turn it on to High/Cook. Place the brisket in the pot, add the charred onions, the carrots, miso, whole garlic cloves, one tablespoon of the butter and the strained spices. Cover with room-temperature water and set the timer to cook for 4 hours.
About half an hour before the brisket is done, place the potatoes into a 4-quart All-Clad saucepot. Add 1 cup of water and the ½ teaspoon of sea salt. Cover and bring to a boil and then simmer until the potatoes are tender, about 20-25 minutes. Drain away the water, put the potatoes back in the pot and add the Brussels sprouts. Cover again and cook for three minutes. Add two tablespoons of the butter to the pot and stir well to melt the butter, glazing the potatoes and the Brussels leaves. Stir the chopped dill fronds into the potatoes and Brussels.
Place the shallots and the vinegar in a small All-Clad saucepot and reduce by half. Turn the heat down to a bare simmer and slowly whisk in the cold remaining butter. Finish with mustard and feel free to adjust the consistency with a little bit of room temperature water.
Check the brisket and make sure it’s really tender. A paring knife should plunge into the meat with little resistance. If it’s tough, cook longer. If it’s tender, remove the brisket and slice it against the grain. Place the potatoes and the Brussels on a large platter and arrange the meat over top. Circle with the mustard sauce and serve.