Scorch tomatoes over charcoal grill, preferably over mesquite. Cool slightly.
Cook chorizo in large saucepan. Add chile, onion, oregano and garlic and sauté until onion is transparent. Add unpeeled tomatoes and chicken broth. Bring to boil. Simmer 10 to 15 minutes. Add cream, salt, white pepper and cayenne.
Purée soup in batches in blender until smooth. Return to pot. Add corn and stir to heat. Ladle into heated bowls. Using separate squeeze bottles, drizzle Crema Fresca and Avocado Sauce over soup, or dollop over soup, if desired. Garnish with cilantro sprigs.
Crema Fresca: In bowl mix sour cream and half and half thoroughly. Pour into squeeze bottles, if desired.
Place avocado, jalapeño juice, cilantro, onion, Serrano chile, garlic, salt and water in blender container and blend until thick liquid that can be squeezed from bottle is formed. Add more water, if necessary.Makes 8 to 10 Source: