A general method for soup, including stock ∞
When making soup, don’t discard the flavour in the peelings and skins — instead use them to make a vegetable stock. Simply put all the off-cuts, tops and tails, onion skins, peelings etc. in the pan and boil up with water whist you chop up the vegetables. Once this has simmered for 15 minutes or so, set aside the liquid and discard the boiled up skins. I tend to use a large pan with a colander sitting in it to collect the stock.
After rinsing the pan out, fry the onions (and leeks if using them) until starting to soften, then add the other vegetables and sauté for around 10 minutes, before adding the stock — making sure not to disturb any soil residue in the bottom (an added bonus of organic produce).
Season to taste, then simmer until cooked — perhaps half an hour. Then either leave chunky or blend as desired.
Simple really.