Mix brown sugar, salt, pepper, and garlic powder in a bowl.

Preheat oven to 275 degrees Fahrenheit.

Fill the lower half of a 2-piece broiler pan with hot water.

Place the ribs on the top half of the broiler pan.

Rub the brown sugar mixture liberally over each rack of ribs.

Cover the pan tightly with heavy-duty aluminum foil, ensuring no heat escapes. Double wrap if necessary.

Place in the oven and bake for 3 to 5 hours.

Remove the foil carefully.

Cut the ribs into manageable lengths for grilling.

Brush the ribs with barbecue sauce.

Grill over high heat (gas or charcoal) for 2-3 minutes per side.

Serve immediately.