When you go to purchase a corned beef brisket, there will be every size and shape and weights ranging from 2.5 to 4 lbs usually with most of them right around 3 pounds.
Look for one that is of even thickness side to side and end to end and has a nice fat cap of about ¼ inch thick.
Corned beef briskets are very salty and if you like it that way, then you can skip this step but if you want to remove some of that salt, it's pretty easy to do by simply soaking it in cold water in the fridge for several hours.
Change out the water every 30-45 minutes.
The longer you soak, the more salt is removed but typically 3-4 hours is plenty.
I don't use the seasoning packet that is often included in the package but if you want to use it, do so before you add the rub and rub it all over the meat to get even distribution of the spices, herbs and seeds.
If you see any clumps or patches of fat on the corned beed brisket other than the on the fat cap side, you might consider removing it with a sharp knife. It's not something you have to do but it will improve the aesthetics and I am of the persuasion that we eat with our eyes as much as anything else so it's important for the end product to look as good and “well put together” as it possibly can.
Now we are ready to season the meat, place it fat cap down on a cutting board or down in a pan to contain the mess.
Apply a good coat of horseradish mustard such as Dijon, Grey Poupon, etc. onto the top and sides of the brisket (fat cap side is down).
Sprinkle Jeff's original rub (Purchase formula here | Purchase bottled rub) liberally onto the top and sides of the brisket and pat it into place lightly with your hands or a fork but do not rub it in. We want to create a nice flavorful crust.
Turn the meat over carefully to fat cap side up.
Repeat the horseradish mustard and Jeff's original rub (Purchase formula here | Purchase bottled rub) on the fat cap side.
The corned beef brisket flat is ready to go into the smoker.
I did mine the night before so it went over a pan, fat cap up, and into the fridge ready to go into the smoker the next morning.
Place the meat directly on the rack or you can leave it on a pan with rack, a cooling rack or a grill pan depending on what is convenient for you.
If you're using a smoker with multiple racks, you might consider placing the meat on an upper rack with a pan just below it to catch drippings.
Allow the meat to cook in the smoker for about 3 hours or until it reaches 140°F in the thickest part of the meat.
I use the “Smoke” thermometer by Thermoworks almost exclusively to monitor temperature.
You can continue to add smoke throughout this initial smoke time.
When the corned beef brisket has reached 140°F and has been cooking for about 3 hours (varies by meat thickness), it is time to do some braising to tenderize the meat.
The horseradish mustard really goes well with the smoked corned beef and in this variation, I have mixed the horseradish mustard with equal parts of my barbecue sauce (Purchase formula here | Purchase bottled sauce). This was so good I was licking the spoon.. of course, I love horseradish so the new combination of flavors was amazing!
Use about ½ cup of Jeff's original barbecue sauce (Purchase formula here | Purchase bottled sauce) with about ½ cup of the horseradish mustard and stir to combine. Make a little extra if you want extra for using later on a sandwich.
Lay down a pad of the mustard in the bottom of a foil pan and lay the meat, still fat cap up, onto the mustard.
Brush a good layer of the mustard sauce onto the top of the fat cap as well. Be generous!
Cover the top of the pan tightly with foil and place it back into the smoker. The oven can also be used in this last stage of the process since the meat is covered in foil.
Note: It is important to continue monitoring the temperature of the meat so make sure a probe is inserted into the thickest part of the meat and that the foil is sealed around the probe wire. You can also place a small hole in the foil top to push the probe through.
With the meat covered in foil, there is no need to continue adding smoke, maintain the heat at 225-240°F until the thickest part of the meat reaches about 195°F.
Let the meat rest for at least 30 minutes or up to an hour in the foil with a thick towel laid over the foiled top or you can leave it in the smoker or oven at 140-170°F during the resting period if you so desire.
Remove the meat from the pan and onto a cutting board or plate.
Slice into pieces the thickness of a pencil and across the grain for best results.