Heat the grill over medium high heat. Skewer chicken. In a shallow dish, combine lemon zest and juice with extra-virgin olive oil. Reserve 1/4 of the marinade. Coat chicken tenders in marinade and season generously on both sides with coarse black pepper. Season chicken tenders lightly with salt. Cook tenders in 2 or 3 batches, a single layer, in a very hot grill. Chicken tenders will cook 3 minutes on each side. Transfer to a serving platter and brush with the reserved marinade.