Process first 4 ingredients in a food processor until pureed. Pour mixture through a wire-mesh strainer into a bowl, pressing with back of a spoon against strainer to squeeze out juice; discard solids. Stir in lemon juice and next 3 ingredients. Cover and chill until ready to serve.
Preheat oven to 350°.
Spread butter over one side of each baguette slice. Place bread, butter-side up, on a baking sheet. Bake 10 minutes or until golden brown. Spread the croutons with goat cheese; set aside.
Heat oil in a skillet over medium-high heat. Add scallops. Sauté 2 minutes or until done.
Ladle soup into 4 bowls; top with a goat-cheese crouton. Divide scallops evenly over croutons. Top with mango.