I love the roasting method for soups as not only can you just chop everything, chuck it in a roasting tin and forget about it, but I think that it really gives soup and incredible depth of flavour.
Even the fairly sad looking salad tomatoes from the supermarket can be transformed into a richly delicious soup! You could use the pre-roasted peppers in brine for this (they work well), but often you can pick up great value multipacks of peppers in the supermarket that are perfect for soup making, so whatever your preference would be fine!
I have specified ‘salt to taste’ as this can be quite personal, the right amount of salt can take the soup from tasting a little bit bland, to tasting wonderful, so just add it in slowly and taste as you go to get it right (too salty soup isn’t nice either!).
If you like a bit of heat then top this off with some chilli sauce such as sriracha.