Mix the salt, pepper, garlic powder, and cayenne powder in a mixing bowl. Set aside.
Slice chicken breast thinly lengthways, 3 pieces per breast. Season chicken breast with the spice mixture and place in the refrigerator for 1 hour.
Place 4 firelighters cubes equally spaced apart at the bottom of your grill. Light the cubes. Place the charcoal grate back inside the unit and lay 30 charcoal briquettes on the charcoal grate (2 layers of 3 by 15 briquettes).
Once firelighters have burnt out and charcoal is hot (roughly 25 minutes) place the cooking grill back on the top of the unit.
Spread the lemon slices evenly across the grill.
Lay the chicken breast slices out evenly across the grill, on top of the lemon slices then cook for 10 minutes. Turn the chicken breast pieces and cook until an internal temperature reaches 165 degrees F (74 degrees C).
Remove from the grill and wrap tightly in foil. Allow the chicken to rest for 10 to 15 minutes before serving.