In large soup kettle, saute onions in butter until tender, but not brown. Add flour and let brown, stirring constantly. Add 1 cup half and half and stir until well blended; add remaining liquid ingredients. Using potato masher or pastry blender, coarsely ?mash? potatoes; add to soup pot. Stir in all remaining ingredients. Heat thoroughly, stirring occasionally, to blend in instant potatoes and to prevent scorching. Garnish with chives, if desired.