Do not cut open the bag.
Have the bag in the fridgerator overnight if frozen to thaw it out.
Warm a pot of water to 150-160 degrees. Low heat essentially on a gas stove. Do not boil the water.
Put the bag in the water for 12 minutes fully submerged. Push it down occasionally if it floats up
After 15 minutes, pull the bag out and let it rest for 5 mins. Feel the bag and if the brisket is warm, you are good. You don't want it too hot.
Cut the bag open and serve. if there are juices in the bag still, don't be afraid to pour them over the brisket.
Enjoy
If your tin of brisket is frozen, put it in the fridge to thaw out a few days before (if you can. if you can't, no worries).
Plan how long before eating to start. (add another hour to below if still frozen)
If 2-3 lbs, assume 90 mins.
If 4-6 lbs. assume 2.5 hours
If 2 or more tins, start 4 hours.
NOTE: It is easier to get to temp early and hold vs. being behind / late (trust me)
Remove the tin from the fridge and remove the vacuum seal bag around the tin if present. Do NOT remove the aluminum foil top covering.
Preheat your oven to 225. (250 if the brisket is still frozen)
Put the tin in the oven with aluminum foil covering still on and start your timer
After the given times, check the temperature with a thermometer or your finger. Measure in the middle of tin in the thickest piece. You are looking for 125 - 140 degrees or warm (not hot) the the touch. Check in times are...
2-3 lbs.: 60 mins after start
4-6 lbs: 90 mins after start
Multiple tins. 2 hours after start
Assume it will take some more after this.
Once you hit your desired warm temp, let it rest for 15+ mins (with the tin foil still on).
If you are at temp and you aren't close to eating time, leave the tin in the oven covered but turn off the oven. Should stay warm for an hour or two. Or you can turn your oven on to the lowest setting like 175 if you need to hold it longer.
Once you start eating, I recommend leaving the foil on the half of the container on the side you aren't eating on to keep it warmer and moist for longer.
Enjoy