Turn your smoker to the smoke setting. When it reaches 225 - 250 degrees, close the lid.
Rinse the meat under cold water and blot it dry with a paper towel.
Combine cumin, salt, chili powder, pepper and sugar in a bowl. Rub all over the meat.
Place brisket in aluminum foil pan fat side up.
Baste with juices that accumulate every hour or so.
Smoke brisket until internal temperature reaches 205 degrees and the internal probe slips in like butter. This may take 10 -13 hours depending on the size of the brisket. (To speed things up, you can wrap the meat in peach butter paper once it reaches 165 degrees and place it on the grill.
Remove the brisket from the grill and let it sit for 45 to 60 minutes. Then transfer it to a carving board and slice it thinly against the grain. (The grain is the way the muscles are aligned. Cutting against the grain and not parallel to it will ensure you get a tender cut.) Top with drippings if desired.