Clean the ribs, and remove all excess fat and gristle from the bone side of the slab(s). Cut slabs so they will fit into a big pot. Cover with water, bring to a boil and cook for 10 minutes. Remove ribs from pot, pat dry and rub thoroughly with your choice of marinades. Store covered in refrigerator for a few hours or overnight. After cooking thoroughly on your outdoor grill (Do NOT use barbecue sauce at this point.), place ribs into a baking dish, cover with a damp towel (not a paper towel, but a terrycloth one). Cover tightly with foil. Place into oven at 200° to keep warm and moist while you grill more ribs or are ready to serve them. When you're almost ready to serve your ribs, remove them from the oven, remove the foil and towel, and brush the ribs generously with your barbecue sauce. Place them back into the oven and bake uncovered at 350° for 10 or 15 minutes, just until the sauce is cooked in. NOTE: If preparing a lot of ribs for a big crowd, and the ribs will be in the oven for an extended period before serving, make sure the towel stays very moist.