01 - Preheat oven to 375°F. Pat turkey breast completely dry with paper towels, then position on a rack set inside a roasting pan.
02 - Combine olive oil, rosemary, thyme, sage, garlic, salt, pepper, and lemon zest in a small bowl, mixing until a cohesive paste forms.
03 - Carefully loosen the turkey skin without tearing, then massage half the herb paste directly onto the meat beneath. Spread remaining paste evenly across the skin surface.
04 - Scatter lemon and onion slices across the roasting pan bottom, then pour in chicken broth.
05 - Set turkey breast skin-side up on the rack, suspended above the aromatic bed.
06 - Roast 1 hour 10 minutes to 1 hour 20 minutes, basting with accumulated pan juices once or twice, until internal temperature registers 165°F at the thickest point.
07 - Transfer to a cutting board, tent loosely with foil, and rest 10–15 minutes to allow juices to redistribute before slicing against the grain.