Finely slice an onion, shred and wash 2 leeks well, chop three medium size potatoes. Sweat in a pan with a good fitting lid with some light olive oil, butter and a small splash of water (stops the potatoes sticking and allows them to steam a bit). When all a little softened, add a mix of water, milk and stock powder then cook for a further 5 mins or so. Waxy new potatoes or old floury potatoes can be used and it's up to you whether or not to peel all or some of them. Add some chives, spring onions or triangular leeks at the end of cooking to add a fresh taste.