Prep. Skin 'n' trim the slab. Cut the slab into individual bones trying to leave the same amount of meat on all sides of all bones.
Fire up. Set up the grill for 2-zone cooking or fire up your smoker and shoot for about 225°F on the indirect side.
Cook. Place the ribs over indirect heat. Put the lid on but resist the temptation to add wood. I think it clashes with the sauce. After 2 hours baby backs should be ready for sauce. They cook a lot faster when cut into individual bones than when cooked as a slab. Paint both sides with sauce or dip them in the sauce and put them back on for about 15 minutes to bake it on. One coat should be enough.
Serve. Just before serving, sprinkle them with the green onions as a garnish. If anyone reaches for a knife and fork, throw them out.
Notes
Optional. If you like the high heat of wasabi, put a dab on your plate and dip the meat into the green paste.