1) Heat oil in saucepan and saut shallot for 2 minutes.

2) Add potato and stock, bring to a boil. Cover and simmer 15 minutes.Stir in the lettuce and tarragon.When lettuce has wilted (almost immediately) remove from heat and pure in a blender. Refrigerate until chilled.When ready to serve, ladle into bowls, spoon 2 tsp of yogurt onto each serving, sprinkle with bacon and basil.