The truth is the fat does not really soak into the meat at all, but runs down the meat and into the fire. This process causes the heat to fluctuate greatly while cooking, creating a very uneven and unpredictable barbecue experience.
Cooking with the fat side down allows the fat on the bottom to just drip onto the heat source, creating delicious smoke flavor that rises back up and through to the meat. The connective tissue within the meat is what keeps it tender and moist. The tissue melts when the internal temperature of the meat reaches 160 degrees Fahrenheit. That moisture from the connective tissue releases into the meat, making it tender.
Using this fat-down method, you really do not have to buy the full-sized brisket (10+lbs.). You can cook the smaller, already-trimmed brisket that is common in many supermarkets, and is better suited for smaller families or groups.
One method of cooking barbecue beef brisket, using a charcoal grill, allows you to barbecue a brisket, or another large cut of meat, for up to 12 hours, keeping the heat low, slow and even. It is the perfect method for cooking overnight, as it pretty much does all the work itself.
1) Lay the brisket, with the fat side down, on a clean work surface. Trim off the hard fat, if any. Peel off the tough membrane that might be on the surface of the meat.
2) In a medium bowl, mix up a rub using 2 tablespoons of each of these ingredients:
-ground black pepper
Also add and mix 2 teaspoons of each of these:
Cover and rub in this mix all over the brisket. Put the brisket back into the refrigerator. Once the fire is ready, it will go straight to the smoker. This gives the brisket the best smoke ring.
3) Using a smoker like the Weber above, fill the bottom ring with a chimney starter full of unlit charcoal briquettes. Light another 15-20 briquettes in the chimney starter. Once they start burning into flames and turning ashy, carefully pour them over the unlit briquettes you placed in the ring. Add wood chunks on top, if desired. Open all bottom vents completely.
4) Place the center section on top of the bottom section, and place the water pan on top. Fill the pan with water and lay in the cooking grates. Clean the top cooking grate with a wire brush. Lay the brisket, with the fat side down, on the top grate. Put the lid on the smoker, with the top vent wide open. Place a thermometer in one of the vent holes in order to watch the temperature inside the smoker. Close the bottom vents to about halfway. The temperature in the smoker will fall to about 250 degrees, at which time you will close the bottom bents 3/4 of the way.
5) Your barbecue beef brisket will take about 1 1/2 hours per pound to cook properly. The internal temperature is the most important indicator of doneness, where it should reach 190 degrees in the thickest section of the meat. You should not have to add charcoal through the whole cooking process. Just adjust the bottom vents occasionally to maintain the temperature between 225 and 250 degrees fahrenheit. You may need to refill the water pan (use warm water) sometime through the second part of smoking.
6) Once the internal temperature of the thickest part of the brisket reaches 190 degrees, remove it from the smoker, and lightly wrap in two layers of aluminum foil. Place the brisket in a cooler (with no ice), and let rest for about 3 hours. This allows the brisket to further tenderize while it stays hot in the cooler.
7) When ready to serve, unwrap the barbecue beef brisket, preserving the juices. Pour the juices into a bowl for serving, or use these juices to make a barbecue sauce of your choice.
8) Slide a small knife between the two sections, and separate the muscles. Trim any excess fat from both sections and slice the meat of the bottom part against the grain. The top section is best chopped up for sandwiches, or just eating. Serve warm with the juices or barbecue sauce on the side.
What you end up with is the finest barbecue beef brisket anywhere. Enjoy.