Place dried mushrooms in medium bowl. Cover with 2 cups hot water ,and let stand 30 minutes. Drain mushrooms, reserving soaking liquid. Bring soaking liquid and broth to a simmer in saucepan over medium heat. Cover, and keep warm.
Heat 1 1/2 tsp. oil in saucepan over medium heat. Add rehydrated mushrooms and 1/4 tsp. salt; sauté 2 minutes, or until mushrooms are tender. Transfer mushrooms to plate; set aside.
Heat remaining 1 1/2 tsp. oil in same saucepan over medium heat. Add fresh mushrooms, shallot, pepper, and remaining 1/4 tsp. salt; cook 2 minutes, stirring frequently. Add garlic, and cook 30 seconds, or until fragrant.
Increase heat to medium-high, and stir in sherry. Simmer 3 minutes, or until liquid is reduced by half. Whisk flour into broth mixture. Stir broth mixture into mushroom mixture, and bring to a boil. Reduce heat to medium-low, and simmer 30 minutes.
Transfer soup to blender or food processor, and purée until smooth.
Return soup to pot; stir in creamer and reserved rehydrated mushrooms, reserving a few for garnish, if using.