Turn an oven to broil setting. Cut the bell peppers in half, remove the seeds and set the peppers aside. To broil the peppers, place them on a sheet of tinfoil that is placed on a cookie sheet. Flatten the peppers with your hand so the skins will all evenly broil and cook. Broil for about 6-10 minutes on high broil, watching them closely. When the peppers are all charred and mostly black or dark brown, remove them from the oven. Wrap up the peppers in the tinfoil to trap in all the moisture. After a few minutes, remove the skins from the peppers, and discard all the tinfoil and skin. Set the roasted peppers aside. Dice the onions into small pieces. Add the onions, olive oil and the garlic to the soup pot. Saute until the onions are soft and tender. Add the roasted peppers, vinegar and Sriracha. Continue to saute for a minute and then add the chicken stock, whipping cream, spaghetti sauce (or canned tomatoes), red pepper flakes, salt and pepper. Let the soup simmer for 3-5 minutes. Puree all of the soup together until completely smooth with a hand wand/blender or place cups at a time in a food processor (be careful with the hot soup mixture). Once the soup is smooth, you can top with fresh basil and a swirl of extra cream (optional) to serve.
Notes
HEALTHIER OPTION: Use whole or 2 % milk instead of the heavy cream.