In a medium bowl, combine the dark brown sugar, Dijon mustard, ground coriander, and minced jalapeño. Add a generous pinch of kosher salt and freshly ground black pepper, stirring until everything is well blended. Pour this mixture into a large resealable plastic bag. Add the chicken drumsticks and turn them over several times to make sure they are fully coated. Seal the bag, squeezing out any air, and place it in the fridge to marinate overnight.

Prepare your grill and oil the grates to prevent sticking. Take the chicken out of the marinade, allowing any excess to drip off. Season the drumsticks once again with a light sprinkle of salt and pepper. Grill them over moderately high heat, turning frequently to achieve a golden-brown exterior, which should take around 10 to 12 minutes. Once browned, transfer the drumsticks to a plate.

For smoking, wrap the soaked wood chips in a foil packet, making sure to poke holes in the top to allow smoke to escape. Remove the grill grate, turn off the heat on one side of the grill, or rake the hot coals to one side if using a charcoal grill. Place the foil packet directly on the coals or flames, then replace the grate. When the wood chips start to emit smoke, place the chicken back on the grill over the cooler, indirect heat. Cover the grill and let the chicken smoke for about 30 minutes, or until the internal temperature reaches 165°F when checked with an instant-read thermometer.

Once done, transfer the smoked chicken legs to a serving platter and enjoy.