Although many slow cooker soup recipes, have lengthy cooking times, the actual preparation time for most is minimal, and they can then be left simmering on a low setting all day or overnight. Most soups benefit from long, gentle cooking, so there is no need to worry if they are left for a a little longer than intended.
A good home-made stock forms the base of many soups so it is well worth making large batches of stock and freezing it in convenient quantities. Alternatively, use good-quality ready-made stock from the supermarket.
There are two basic techniques for making slow cooker soups. The easiest is to place the prepared ingredients in the ceramic cooking pot with either cold or near-boiling stock. This produces a fresh flavoured soup with a low fat content and is a good method for vegetable soups. However, it is less suitable for recipes containing onion, which take a long times to soften. The second, more usual, method is to suite or fry onions, other vegetables and/or meat in a frying pan before placing in the cooking pot. In some recipes, vegetables are simply softened, but in others they may be lightly browned, giving a richer flavour and deeper colour.
Mixed vegetable soup
Almost any vegetable can be made soup, but fro the best results, use the freshest, seasonal ingredients.
675g/1 ½ lb mixed vegetables, such as carrots, celery, parsnips, potatoes 25g/1 oz/2 tbps butter 1 onion, fanely chopped 5ml/1 tsp dried mixed herbs 900ml/1 ½ pints/3 ¾ cups near-boiling vegetable stock 150ml/ ¼ pints/ 2/3 cup milk or single (light) cream (optional) salt and ground black pepper
- Prepare the mixed vegetables, then cut them into 5mm/ ¼ in slices, sticks or dice to ensure that they cook evenly and within the recommended time. Melt the butter in a frying pan, add the onion and fry gently, stirring frequently, for 10 minutes, until softened but not coloured.
- melt the butter in a frying pan, add the onion and fry gently, stirring frequently, for 10 minutes, until softened, but not coloured.
- Add the chopped vegetables to the pan and fry for 2-3 minutes. Transfer the vegetables to the ceramic cooking pot and switch the slow cooker to low.
- Sprinkle over the dried mixed herbs, then pour in the stock. If you are using vegetables with a high water content, such as courgettes (zucchini) or squash, reduce the quantity of liquid. Others such as potatoes and dried vegetables, soak up cooking juice, so add a little more liquid to compensate. (Bear in mind that it is easier to dilute the soup at the end of cooking, than to try to thicken a watery soup.)
- Make sure that there is a gap of at least 2cm/ ¾ in between the liquid and the top of the slow cooker, then cover with the lid and cook for 7-12 hours, or until the vegetables are tender.
- If using milk or cream, stir this in and cook for a further 30 minutes to bring the soup back to boiling point. (Do not heat for longer than this because long heating may cause the soup to separate.) season to taste, then serve.
A few ladlefuls of soup can be pureed then stirred back into the remaining soup to thicken it, or the entire soup can be pureed to make a wonderfully smooth, velvety soup. When making chilled pureed soup, it is best to adjust the consistency after chilling because the soup will thicken considerably as it cools.
The simplest way to make pureed soup is using a hand-held blender. It can be pureed while still in the slow cooker, and will not need reheating. You can also use a food processor or blender, but do not over-fill it because it may flood over the top. Most soups will need to be processed in two or more batches and, unless being served cold, will need to be reheated in the slow cooker or in a pan on the stovetop.
Soft vegetable soups can be pureed by hand. Press the mixture through a fine stainless steel or plastic sieve, using a wooden “mushroom” or a large spoon. Alternatively, press the vegetables through a mouli-legumes, then stir in the cooking liquid. The soup will need to be reheated if serving hot.
There are several ways to thicken soups. Cornflour (cornstarch) or arrowroot are probably the simplest. They can be blended with a little cold water to make a smooth paste, then stirred or whisked into the hot soup. Cornflour will thicken boiling liquid instantly, but takes about 10 minutes to loss its raw flavour. Arrowroot thickens as soon as it reaches boiling point, but will become slightly thinner with prolonged cooking, so add in the last few minutes of cooking.
Plan (all-purpose) flour can be sprinkled over fried onion before string in the stock, or blended with an equal quantity of softened butter or double (heavy) cream and whisked into the finished soup a little a time, cooking for few minutes to thicken. Allow the soup to cook for at least 5 minutes to avoid a raw flour flavour.
Beaten eggs, egg yolks or a mixture of eggs and cream can be used to thicken and enrich smooth soups. Always turn off the heat and allow the soup to cool slightly before whisking in the egg mixture, otherwise it may curdle. Breadcrumbs are sometimes used to thicken rustic and chilled soups. The breadcrumbs are stirred into the finished soup to soak up and thicken the liquid.
Adding a pretty garnish give the final flourish as you serve soup, and can be as simple or complex as you like. A swirl of cream, crème fraiche or yogurt, followed by a sprinkling of paprika or ground black pepper, can look great with smooth soups. Fresh chopped herbs make another simple but stylish garnish, adding colour, flavour and texture. Use strong herbs, such as sage and rosemary, in moderation. For a richly flavoured garnish, try adding a spoonful or swirl of pesto. It works especially well with Italian and Mediterranean soups. Grated, shaved or crumbled cheeses also work well and are particularly good with vegetable and bean soups. Strongly flavoured cheeses, such as Parmesan, Cheddar or a crumbly cheese, such as Stilton, are ideal.
To add more substance, flavour and texture to soups, try sprinkling over croutons or fried breadcrumbs. These are a classic soup garnish and they add a crunchy texture that works with both smooth and chunky soups. To make croutons, cut thick slices of day-old bread (any type will do) into cubes. Shallow-fry in hot olive oil, turning them continuously, so that the cubes brown evenly, then drain on kitchen paper. Fried breadcrumbs can be made in the same way, but need less cooking time. To oven-bake croutons, toss them in a little oil, them bake in a shallow roasting pan at 200 /400 /Gas 6 for 12-15 minutes.
Grilled cheesy croutons are the classic topping for French onion soup and can make a dramatic impact floating on top of a bowl of steaming hot soup. Simply rub thin slices of day-old baguette with peeled garlic cloves, then lightly toast both sides under a hot grill (broiler). Sprinkle one side with grated Cheddar or Parmesan cheese, or sliced goat’s cheese, and put under a hot grill until melted. Float one or two croutes on top of the soup just before serving.