Roast the pepper on foil on the oven rack next to the pan with the corn. Flip it over halfway through roasting.
Put the pepper in a bowl, cover and wait 10 minutes. Then peel, deseed and chop it.
Puree 3/4 of the soup in a blender. Then pour it back into the pot to rewarm it as needed.
Divide the soup into bowls and top with roasted corn and sliced scallions.