In a food processor, pulse the garlic, sage, rosemary, pepper flakes, 1-1/2 Tbs. salt, and 1 tsp. pepper until finely chopped.
Pat the chicken breasts dry with paper towels. Lightly brush both sides of the chicken with olive oil and season each breast with 1 tsp. of the herbed salt. Let stand at room temperature while preparing the grill.
Prepare a gas or charcoal grill fire for direct grilling over medium heat (350°F). Wrap four bricks in heavy-duty aluminum foil.
If using a charcoal grill, sprinkle 1 cup of unsoaked wood chips (preferably oak) over the coals. Replace the grill grate. If using a gas grill, use two layers of heavy-duty aluminum foil to make
a V-shaped packet to hold the wood chips. Set the foil packet between
two burners and add the chips to the foil packet. Replace the grill
Clean the grate with a wire brush and, using tongs, wipe the grate with a paper towel or cloth dipped in oil.
Arrange the breasts skin side down on the grill on a diagonal to the grate. Put a brick on top of each chicken breast. Grill (covered if using a gas grill) until the skin is crisp and golden-brown, 8 to 10 minutes. If flare-ups occur, move the chicken to a different part of the grill.
Using grill mitts or tongs, remove the bricks, flip the chicken over, and replace the bricks. Continue to grill (covered if using a gas grill) until an instant-read thermometer inserted in a thick part of a breast reads 165°F, 8 to 10 minutes more.
Transfer the chicken breasts to a platter or plates and drizzle with additional olive oil. Serve with the lemon wedges and the remaining herb salt on the side.