In a food processor combine the mint leaves, parsley, cilantro, garlic, lemon juice, cumin, and white pepper and process until smooth. Reserve ¼ cup of the marinade in the refrigerator. Pour the rest of marinade into a re-sealable plastic bag.
Put the turkey in the bag with the marinade, and seal. Massage the marinade into the meat, and place on a plate to catch any leaks. Leave in the refrigerator for at least 4 hours, preferably overnight.
Preheat the oven to 400 degrees F. Remove the turkey from the marinade and place on a baking sheet.
Roast the turkey for 20 minutes then pour the reserved marinade over the turkey, turn down the heat to 350 and cook for another 30 minutes, or until the turkey is done. Let rest for 10 minutes before slicing or serving.