In a large bowl, remove corn kernels from cob using a small knife. Set aside. In heavy pot saute onion in olive oil. Add garlic and red pepper. Stir. Season with salt, pepper and cayenne. Cook until vegetables are soft. Add corn and chicken stock. Add potatoes. Cover and simmer until potatoes are tender. Remove 2-3 ladles of soup to a blender and puree. Pour puree back in soup and stir. Serve hot with a dash of Tabasco.