Place the coarsely chopped yellow onion, garlic cloves, yellow mustard, and Worcestershire sauce in a food processor.

Puree the mixture until completely blended into a smooth marinade.

Place the 16-18 pound turkey in a roasting pan fitted with a rack.

Thoroughly rub the outside of the turkey all over with the prepared mustard marinade.

Cover the marinated turkey with plastic wrap to retain moisture.

Refrigerate the turkey for at least overnight, or up to 24 hours.

Preheat the oven to 400 degrees F (200 degrees C).

Remove the refrigerated turkey from the refrigerator and discard the plastic wrap.

Place the marinated turkey in the roasting pan.

Tuck the turkey wings beneath the breast to prevent burning.

Tie the base of the turkey legs together securely with butcher's twine.

Using a pastry brush or bulb baster, baste the turkey with some of the dark malt beverage.

Transfer the turkey to the preheated oven and roast, uncovered, for 3 hours, ensuring even cooking.

Baste the turkey every 30 minutes with the malt beverage to maintain moisture and flavor.

If the turkey breast starts to appear overly dark, cover it loosely with aluminum foil to prevent burning.

Continue to cook the turkey until the juices run clear when pierced, and the internal temperature reaches 160 degrees F (71 degrees C) in the breast and 175 degrees F (80 degrees C) in the leg, as measured by an instant-read thermometer.

Remove the roasted turkey from the oven with care.

Cover the cooked turkey loosely with foil.

Allow the turkey to rest for 30 minutes before carving to allow the juices to redistribute.

Carve the turkey and serve hot with homemade three meat stuffing and cranberry passion fruit sauce on the side.