Mix 2 quarts lukewarm water, sugar, salt, vinegar, garlic, and orange zest in a large bowl.

Stir until sugar and salt dissolve.

Add the pork roast to the brine.

Cover and refrigerate overnight or up to 2 days.

Remove pork from the brine and discard the brine.

Put pork into a glass dish and coat well on all sides with some of the glaze.

Cover and refrigerate for several hours or up to 1 day.

Soak wood chips in a large bowl of water for at least 1 hour.

Prepare a charcoal grill or heat a gas grill to medium-hot for indirect cooking.

Arrange coals on two sides of the grill or turn off burners in the center of the gas grill.

Place the cooking grate in place and let it heat for a few minutes.

Put the pork roast in the center of the grill (not directly over the heat).

Add a small handful of the wood chips to the coals.

If using a gas grill, wrap soaked chips in a foil pouch, pierce it with small holes, and place it directly over the heat source.

Cover the grill and cook on medium-low (about 275 degrees if you have an oven thermometer), basting frequently with some of the red chili glaze.

Cook until an instant-read thermometer registers 160 degrees, about 2 1/2 to 3 hours.

The roast should be very nicely burnished red with some crispy edges.

Let the pork rest on a cutting board for about 20 minutes.

Slice very thinly and serve.