At first glance, a novice barbecue enthusiast might be excused for thinking that baby back ribs should be cooked with their meaty side facing down. The grill's heat comes from below, after all, and it seems intuitive to place the meaty section where it's exposed to the heat. In truth, because ribs are relatively tough and gristly, they require long, slow cooking in indirect heat. The bony concave side of the ribs should always face down, so the thin meaty layer won't overcook during this lengthy process.
The Cooking Process
Season the ribs ahead of time with your favorite dry rub or spice paste, and let them rest for 1 to 24 hours before you begin cooking. The ribs need indirect heat, so after your coals are well established rake them all to one side of your kettle. If you're using a gas grill you can light one side and not the other, or both sides but not the middle. Place the baby back ribs over the unheated portion of your grill with the curved side down, close the lid, and stabilize your grill's temperature at 225 degrees Fahrenheit. After 3 to 4 hours at that temperature, they should be perfectly tender and the rib bones should rotate easily within the meat.