How to Make It
Preheat oven to 190°, then place the frozen roast on a wire rack on a baking sheet. Roast until the internal temperature reaches 140° to 155°, about 8 to 10 hours (start checking it with a thermometer at 7 hours). Remove from the oven and set aside to cool for a few minutes while preparing the brine.
In a pot, heat the water, salt and honey until the salt is dissolved. Remove from heat and add the remaining ingredients, stirring together until the ice is melted. If the brine is still above room temperature, add more ice and stir until melted.
Once the brine is at room temperature, pour it into a gallon-sized resealable bag, then place the roast in the brine. Arrange the bag in the fridge so that it stays upright and the meat is fully submerged in the brine; soak for 5 hours.
Remove the roast from the brine and pat dry. It can be sliced immediately, but for best results, put it back into the fridge in a dry, resealable bag for one more day for better flavor.