1. Remove the packets of giblets (if any) from the body cavities of the game hens and set aside for another use. Remove and discard the fat just inside the body and neck cavities. Rinse the game hens, inside and out, under cold running water and then drain and blot dry, inside and out, with paper towels.

2. Spatchcock a hen: Place a hen on its breast. Using poultry shears and starting at the neck end, cut out the backbone, making one lengthwise cut on either side. Remove and discard the backbone or save it for stock. Fold the game hen open like a book, skin side down. Use a paring knife to cut along each side of the breastbone. Run your thumbs firmly along both sides of the breastbone and white cartilage, then pull them out. Cut off the wing tips and trim off any loose skin. Pull down on the legs to lay them flat. Repeat with the remaining game hens.

3. Place the hens in a large nonreactive baking dish, sprinkle both sides with the cracked black peppercorns and hot red pepper flakes and season with salt. Sprinkle the garlic and sage over both sides of the game hens. Pour the lemon juice over the hens, followed by the olive oil, turning the hens to coat both sides. Let the hens marinate in the refrigerator, covered, for 1 to 2 hours.

4. Set up the grill for direct grilling and preheat to medium. When ready to cook, brush and oil the grill grate. Arrange the spatchcocked game hens skin side down on the grate. Place a brick on top of each hen so that it covers as much of the bird as possible. Grill the game hens until the skin is golden brown, 8 to 10 minutes.

5. Remove the bricks and carefully turn over the hens using tongs and a spatula. Re-cover with the bricks and continue grilling until the second side is a dark golden brown and the hens are cooked through, 8 to 10 minutes more. You may get some flare-ups as melting fat hits the fire. If this happens, move the hens to another section of the grill. You can tame any really serious flare-ups with a squirt from a water pistol (1 or 2 squirts to control the flames are okay, but don’t overdo it or you’ll put out the fire). The hens are done when an instant-read meat thermometer inserted into the thickest part of a thigh (but not touching the bone) registers 170°F.

6. Transfer the hens to a platter and garnish with sage and lemon wedges.