Preparation Heat oil in a 6-quart heavy pot over moderate heat until hot but not smoking, then cook shallots, ginger, garlic, and curry powder, stirring, until shallots are golden, about 2 minutes. Stir in wine, tarragon, and mussels and cook, covered, until mussels just open wide, checking frequently after 3 minutes and transferring opened mussels to a bowl. (Discard any mussels that remain unopened after 6 minutes.) Add stock, carrot juice, and clam juice to pot and bring to a simmer, stirring occasionally. Whisk lime juice into sour cream in a small bowl. Add lime mixture in a stream to soup, whisking until smooth, then season with salt and pepper. Return mussels to pot and cook over low heat, stirring occasionally, until just heated through (do not let boil).
Preparation Heat oil in a 6-quart heavy pot over moderate heat until hot but not smoking, then cook shallots, ginger, garlic, and curry powder, stirring, until shallots are golden, about 2 minutes. Stir in wine, tarragon, and mussels and cook, covered, until mussels just open wide, checking frequently after 3 minutes and transferring opened mussels to a bowl. (Discard any mussels that remain unopened after 6 minutes.) Add stock, carrot juice, and clam juice to pot and bring to a simmer, stirring occasionally. Whisk lime juice into sour cream in a small bowl. Add lime mixture in a stream to soup, whisking until smooth, then season with salt and pepper. Return mussels to pot and cook over low heat, stirring occasionally, until just heated through (do not let boil).