In a large saucepan over medium-high heat, add the olive oil.
Stir in the onion, garlic, tomatoes, red pepper flakes, black pepper and salt, to taste. Simmer for 10 to 12 minutes. Add the chicken stock and chicken bouillon and cook for an additional 10 minutes. Stir in the sherry at the last minute and remove from the heat. Allow to cool before adding it to a blender. Puree until smooth and return to the pot, over low heat, to keep warm until ready to serve.