Combine first 4 ingredients in slow cooker on high. Saute mushrooms in butter in until tender. Add to slow cooker. Once soup is hot, add cream of mushroom soup, stirring until well blended. Season to taste with Adobo. Cook on high for 4 hours or low for 6-8 hours. One hour before serving, mix flour with 1/3 coup hot water until dissolved and add to soup to thicken. 30 minutes before serving, add milk and sherry.