Rinse turkey with a mixture of water and lemon, and pat dry with a paper towel. Let turkey sit in the roasting pan while you prepare the seasoning.
In a food processor or blender, mix the cilantro, garlic, onion, cumin, oregano, sazón, salt, and lemon juice.
Rub mixture all over your turkey, both outside and inside the turkey cavity.
Stuff the turkey with celery, carrots, and onions. Place some celery, carrot, and onion pieces in the roasting pan around the turkey. This step is optional.
Preheat oven to 430°F. Place turkey in the oven and bake for about 30 minutes.
After the 30 minutes have passed, lower the oven temperature to 350°F and cover the turkey with aluminum foil. Continue to bake until the turkey reaches a temperature of 165°F, about 3 hours for a 12-pound turkey.
Remove from the oven and let rest for at least 15 minutes before carving.