In a large saucepan, heat the remaining 2 tablespoons of olive oil. Add the corn, leek, celery, parsley, thyme and coriander. Cover and cook over low heat, stirring occasionally, until the vegetables soften, about 10 minutes. Add the remaining 1/2 cup of wine and simmer over moderately high heat until evaporated, about 4 minutes. Add the flour and cook, stirring, for 1 minute. Gradually stir in the clam juice and bring to a boil over moderately high heat, stirring constantly. Reduce the heat to low, cover and simmer for 5 minutes. Transfer the soup to a blender and puree. Strain the puree through a coarse sieve and return it to the large saucepan.