How to cook leeks

Everything you need to know and more about this understated vegetable. Discover how to prepare, cook and store leeks...
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  • Leeks are one of the most versatile vegetables. They bring so much flavour to a dish by adding a delicate sweetness and freshness.

    Wondering how to cook leeks? We’re here to help! Like onions, leeks are part of the allium family. This is evident from their flavour. When eaten raw leeks have a mild onion-like sharpness, but thankfully they don’t make your eyes water when chopping them as onions do. Once cooked the flavour of leeks mellows and sweetens so they are a great addition to lots of dishes.

    As well as being extremely tasty leeks have health benefits. They are packed with vitamin B6, vitamin C, folate and iron. Stewart Aspinall, Leek farmer and British Leek Growers Association chairman explains that Leeks are not only easier to digest than onions, they also pack quite a health punch!

    Leeks have ‘antiseptic, diuretic and anti-arthritic properties. A source of inulin, they are also a natural prebiotic, so great for gut health. Leeks contain on eighth of an adults daily potassium requirement, so encouraging the efficient functioning of kidneys.’

    When are leeks in season?

    Leeks thrive in cooler climates, so are an ideal crop to grow in the UK. They shoot up mid-August and are in season until March or April. Leeks are a winter vegetable, considered to be at their best from November to April, however, you can buy leeks from the supermarket all year round.

    They are long and cylindrical, and from top to bottom illustrate a white to green ombre effect. The white half grows below the soil as the floppy green ends emerge.

    Leeks growing outside

    In the supermarket or grocers, most of the wild green tops have been lopped off, leaving just what is intended to be eaten. Leeks are extremely versatile and can be used in many leek recipes. You can use leeks as an aromatic to add flavour as you would use onions. Alternatively, leeks make a delectable side in their own right.

    Leeks vary in size but are typically cut to about 30 – 40 cm long. You can also buy immature baby leeks, which can be as small as spring onions. But don’t be fooled, these babies have a sweeter flavour and are much less astringent than spring onions.

    How to prepare leeks

    To prepare leeks begin by washing the outside. Next, slice lengthways, as in the image below, and wash and grit and mud from between the leaves. It’s essential to wash leeks thoroughly as there can often be mud trapped inside. If not washed off the dirt will give your final dish a gritty texture.

    Use a knife to remove the very end where the roots were growing from and discard. The remainder of the leek is edible and can be chopped as desired. If eating raw we recommend slicing finely. If cooking you can cut nice chunky pieces for stews or smaller for other recipes.

    how to cut leeks to wash them

    Do I have to boil leeks before frying?

    You do not need to boil leeks before frying them. To fry leeks, we recommend cooking leeks in butter over a low to medium heat. Leeks are a little more delicate than onions, the fine layers can burn if the temperature of the frying pan is very hot.

    To make the leeks soft as a base for adding other ingredients to you should sweat them. To sweat vegetables, put a lid onto the pan, they will release steam that will help to gently cook them. Every few minutes give them a stir to help them to cook evenly.

    Fried leeks cooked in butter are also a tasty side dish favoured by Delia Smith. In Delia’s Complete How to Cook she explains ‘This is my favourite way of cooking leeks – very gently, in their own juices and served as a vegetable.’ It’s very easy too, just cook gently in butter with seasoning for about 5 mins. Stir so they cook evenly.

    How to cook leeks

    Leeks can be cooked in many ways. They can be boiled, roasted, braised, sauteéd or steamed. They are extremely versatile and can be served as a side or used in recipes. Leeks are typically quick and easy to cook. However, they require gentle cooking as the layers are thin and can burn. You can even cook leeks in the microwave, which is a fantastic way to prepare them quickly for adding to things such as warm salads or sarnies.

    GoodtoKnow Food Writer Jessica Ransom is a big fan of leeks. We asked her how she likes to cook hers and she said ‘I love them in a leek gratin or simply softened in butter for a low maintenance side dish to a Sunday roast. Leek and potato soup is also one of my go-to recipes when I’m craving something comforting but healthy.’

    How long do leeks take to cook?

    The cooking time of leeks varies depending on the cooking method. Leeks are cooked once soft and tender. Prod with a fork to check the doneness. Here are our cooking times for different methods:

    • Boiled – whole leeks boiled take around 20 mins, cut into chunks they require from 10 – 15 mins cooking time. Boil leeks in salted water.
    • Steaming leeks cut into chunks takes about 25 mins
    • Sauteed leeks sliced into crescents require 5 – 10 mins of cooking time over a gentle heat.
    • Roasted. With the oven set to 160C leeks cut lengthways in half and brushed with oil require about 25 mins of cooking.
    • Braised. First fry the leeks in butter for 5 mins, then cover with vegetable stock and stew slowly for 1hr.

    How to cook leeks in the oven

    1. Heat the oven to 160C/Gas 3. Prepare the leeks as explained above.
    2. Cut the leeks in half lengthways and longways and put onto a roasting tray quite close together. Drizzle with rapeseed or olive oil and sprinkle over sea salt and black pepper.
    3. To avoid the leeks from taking too much colour and burning we cover with foil and cook for 30 mins, then remove the foil and cook for a further 20 mins. You can also cook without foil, just keep an eye on them and turn regularly to avoid scorching the tops.

    Cooking leeks in the oven is a lovely way to cook them as it brings out the sweetness. They can then be served as a side and make a wonderful accompaniment to a Sunday roast dinner. Baby leeks are also great roasted. They look great on the plate as they can be roasted whole. They also take less time. 15 mins should be sufficient.

    roasted leeks and carrots

    Elisa Roche GoodtoKnow Food Director thinks leeks don’t get the recognition they deserve. She explains ‘Leeks are such an underrated vegetable. I like to top and tail them, peel off their outer skin and roast them in a tray with other veggies. Then give each guest at least one whole roasted leek with butter and toasted breadcrumbs thrown on top.’

    Leeks can also be cooked in the oven along with other vegetables. Try our easy recipie for roasted leeks and carrots. It has added thyme and honey to make it extra special.

    How to cook leeks in the microwave

    The easiest and quickest way to cook leeks is in the microwave. Simply put the prepared and chopped leeks in a microwave-safe bowl or dish along with a tablespoon on water. Cook for bursts of 2 mins on the highest setting. Stir between bursts. They will take about 6 mins in total to cook and are ready once tender. Tip away any excess water and mix in a little butter and season.

    The cooked leeks can now be eaten on their own this or if you’re feeling fancy they are fantastic added to mashed potato or pasta sauces.

    Leek, asparagus and pea pastaHow to store leeks

    You should store leeks in the fridge. Storing them correctly in their packaging will lengthen the lifespan. You should expect leeks to be useable for a couple of weeks after buying them.

    We would not recommend freezing leeks raw, however, to avoid wasting leftover leek first fry it in butter or saute cut leeks and then freeze them once cooked. Cooked frozen leek can then be defrosted and added to dishes.

    Top tips for cooking leeks

    When it comes to cooking leeks these are our favourite tips and tricks.

    • When selecting leeks Simon Hopkins recommends finding ‘large fat ones, for the best flavour’.
    • Washing leeks is vital as there is often mud hidden between the layers. If this isn’t removed it will add as undesirable gritty texture to your cooking.
    • The longer you cook leeks the sweater they will become. Jamie Oliver advises that you “invest time in cooking your leeks super-slowly until sticky and sweet.”
    • Leeks are a winter vegetable and a great addition to warming winter comfort foods. They are a flavour match made in heaven with bacon. Try this simple dish: leeks with chestnuts and bacon. And we swear by adding oodles of leeks to our macaroni cheese.

    What’s your favourite way of cooking leeks?