Turn the oven to 450°F In a food processor, finely chop the lemon, olive oil, cilantro, garlic, and cumin.
Cover a shallow roating pan with foil. Arrange the chicken breasts on the foil, skin side up, and spread the lemon mixture over them. Grind a generous amount of black pepper over the chicken and place in the oven. Reduce heat to 325°F.
Roast chicken for 45 minutes, pasting it with its pan juices, until the chicken reaches 170F on an instant-read thermometer.
Alternative roasting method: Roast 1 hour at 300°F.