Preparation

• To make the brine, combine the salt, sugar, water, lemon, peppercorns, mustard seeds, and coriander seeds in a medium saucepan and heat over medium heat, whisking occasionally, until the salt and sugar dissolve, about 5 minutes. Transfer to a medium-large bowl, add the coffee, and refrigerate until cool, about 15 minutes. Put the chicken breasts in the brine and set a pot lid or small plate on top to keep them submerged. Refrigerate them in the brine for 2 to 3 hours.
• Heat a gas grill to high or prepare a hot charcoal fire. If using wood chips with a gas grill, pile them in the smoker box or in a smoker pouch (seeHow to Add Smoke to a Gas Grill). Run your grill on high until you see smoke. If using a charcoal grill, toss the wood chips directly onto the hot coals.
• Drain the chicken and blot dry with paper towels. Lightly brush both sides with the melted butter or oil. Arrange the breasts on the grill at a 45-degree angle to the bars of the grate. Grill until they have grill marks, about 2 minutes, and then rotate them 90 degrees (to get a crosshatch of grill marks) and continue grilling for 2 to 4 minutes. Flip the breasts and cook unitl they’re firm to the touch, another 4 to 6 minutes. Serve immediately.