Prepare the smoker and the brisket

• Preheat your smoker to 250°F (121°C). Use an air probe connected to your Signals to monitor the temp—set high- and low-temp alarms for 275 and 225°F respectively (135 and 107°C)—and, if using, connect your Billows BBQ control fan to it to maintain a proper temperature. 
• Trim the brisket to your liking. Save the trimmings, especially the fat, in a tray to render. 

Make the rub

• In a dry skillet, toast the black peppercorns, Szechuan peppercorns, and fennel seeds until they are toasty and very fragrant. Transfer them to a plate to cool.

• Grind the toasted mixture with the mustard seeds in a spice grinder or mortar and pestle until medium-coarse.
• Combine the resulting mixture with the gochugaru, salt, sugar, and garlic powder. 

Season the brisket

• If your brisket doesn’t feel moist-tacky enough, rub it with yellow mustard. 

• Liberally sprinkle the firecracker rub on the brisket, pressing to adhere. Be generous, but don’t force yourself to use it all. (It’s a good idea to add a little more later on, anyhow!)

Smoke the brisket

• Place the brisket in the smoker and insert two probes—one in the flat, and one in the point—and set the corresponding high-temp alarms on your Signals to 165°F (74°C).
• Place the tray of brisket trimmings in the smoker as well, to render the fat from them. 

• Let the brisket smoke for 3 hours, then spritz it with water or cider vinegar. 
• Continue to smoke until the internal temperature of the flat reaches 165°F (74°C), about 5 hours. 
• When the flat reaches temp, lay the brisket on two overlapping sheets of peach paper. 
• Strain and then pour some of the rendered fat (about 1/2–3/4 C) onto the brisket. Apply a light dusting of more of the firecracker rub to the surface of the brisket. 

• Wrap the brisket well in the peach paper, put it back in the smoker and re-insert the probes. Set the new high-temp alarms for 203°F (95°C). 

• Increase the smoker temp to 300°F (149°C), adjusting the pit-channel alarms accordingly. 
• Smoke until the high-temp alarms sound at 203°F (95°C). 
• Verify the internal temps with your Thermapen ONE. Check for both temperature and tenderness. 

• Remove the brisket from the smoker and allow to rest in a warm environment for at least 1 hour. 
• Unwrap the brisket, slice, and serve!