How to Make It
In a large saucepan, heat the canola oil until just shimmering. Add the chopped onion, yellow bell peppers and jalapeños and cook over moderately low heat, stirring occasionally, until the vegetables begin to soften, about 6 minutes. Add the chicken stock, potato and a pinch each of salt and cayenne pepper and bring to a boil. Cover partially and simmer over moderately low heat until the vegetables are tender, about 25 minutes.
Working in batches, puree the soup in a blender or food processor until smooth. (Alternatively, use an immersion blender to puree the soup.) Return the soup to the saucepan and reheat gently. Stir in the sherry vinegar and season with salt. Ladle the soup into shallow bowls, top with the chopped cilantro and serve.