Preheat the oven to 250 degrees.
Combine cranberries, water, sugar and honey in a saucepan and bring to a boil. Reduce the heat and simmer uncovered for 15 minutes.
Stir in the horseradish, wine, water or stock, tamari and cinnamon. Return to a boil and simmer for 10 minutes. Remove from heat and aside.
In an oven-safe dutch oven or pan large enough to hold the brisket, warm the oil over medium-high heat. Add the brisket and sear for 7-8 minutes until nicely browned. Turn the meat and sear the other side. Pour the cranberry mixture over the meat.
Cover the dutch oven with a lid or foil or transfer meat to a roasting pan and cover with foil. Cook in the preheated oven for 6 hours. Remove the pan from the oven and refrigerate overnight.
To serve, slice brisket across grain and wrap in aluminum foil. Place in a preheated 350 degree oven for 45 minutes until hot.
This recipe is adapted from Bubbe and Me in the Kitchen