Onion Powder Sept 27, 2009 9:42:04 GMT -8 Select PostDeselect PostLink to PostMemberGive GiftBack to Top Post by Jody on Sept 27, 2009 9:42:04 GMT -8 Onion powder is a spice used for seasoning in cooking. It is made from finely ground dehydrated onions, mainly the pungent varieties of bulb onions, which causes the powder to have a very strong smell.