Combine the dark brown sugar, Mexican chili powder, kosher salt, paprika, dried onion flakes, granulated garlic, dried thyme, Mexican oregano, coriander, and cumin in a small food processor or spice grinder to create your rub. Set aside about 1/2 cup for later use.

Prepare the brisket by trimming away any discolored fat, hard fat, or fat between the flat and flap. Leave most of the fat cap intact on one side.

Apply approximately 1-1/2 cups of the spice rub generously to both sides of the meat, working it in thoroughly with your hands.

Wrap the seasoned brisket tightly in plastic wrap or cover it on a sheet pan. Refrigerate for at least 8 hours, preferably overnight, to allow the spices to penetrate the meat.

When ready to smoke, prepare the mop sauce by combining the apple juice, strong coffee, cider vinegar, beer, and 1/2 cup salt in a steam pan.

Reserve about 2 cups of this liquid mixture and combine it with the 1/2 cup of rub you set aside earlier to create your dedicated mopping liquid.

Preheat your smoker to approximately 200°F. Add the wood chips to the smoker box and wait until the smoke is thick.

Place the brisket fat side up in the smoker and begin the smoking process. Mop the meat every 30 to 45 minutes to maintain moisture.

Once the internal temperature reaches 145-150°F (typically after 4-5 hours), wrap the brisket in a double layer of foil and return it to the smoker or transfer to an oven.

Continue cooking until the brisket reaches an internal temperature of 190-195°F.

Remove from heat and allow the brisket to rest in its foil wrapping for 15-20 minutes before slicing against the grain to serve.