Preheat a grill to medium high. Drizzle the lettuce with the olive oil and season with salt and pepper.
Place the lettuce cut-side down on the grill and cook until grill marks appear, about 2 minutes. Rotate 45 degrees and cook until crosshatch marks appear, about 2 more minutes. Transfer to a platter, drizzle with the lemon juice and serve immediately.
Photograph by Steve Giralt
Recipe courtesy of Marc Murphy for Food Network Magazine