Onions & leeks

White onions are great for all types of cooking, while red are generally sweeter and add colour to roast vegetables. Large, white Spanish varieties are sweeter and good for salads too. Buy untrimmed leeks, ideally when in season. You need waste very little leek – use trimmings, well-washed and shredded, in soups in place of onion. Leeks are grown in sandy soil so make sure you wash them well or they will taste gritty.