SAUTE leeks, garlic and thyme in hot oil in stockpot on medium heat until tender.
ADD vegetable stock and potatoes. Bring to boil. Reduce heat to medium-low; cover. Simmer 30 minutes, stirring occasionally.
ADD to blender container in batches; process until pureed. Return to stockpot. Stir in cream. Cook 5 minutes or until heated through, stirring occasionally. Remove from heat. Add mustard; stir with wire whisk until well blended.