Clear broth and a great soup: the rules cooks know

It depends on what you want. For a rich broth, put the meat and bones into cold water and heat slowly: proteins and flavour gradually move into the liquid. If juicy meat matters more than the broth, drop the meat into boiling water: the surface sets fast and keeps the juices in.

For a classic soup you almost always want the first option: cold water, slow heat.

The best broth comes from meat on the bone: bones, cartilage and joints release gelatine — that rich, lip-sticking body. Boneless fillet gives a thin broth.

Cloudiness is tiny bits of coagulated protein and emulsified fat. You get it for two reasons: the scum wasn't skimmed, and the broth boiled hard. A rolling boil literally whips fat and water into an emulsion, like mayonnaise.

The rule: as soon as it comes to the boil, skim all the foam and turn the heat right down — the surface should barely tremble, with the odd bubble at the edge. Leave the lid ajar.

An old restaurant trick is the egg-white raft. The white coagulates and, like a filter, traps all the fine particles.

For 2 litres of broth take 1–2 egg whites. Whisk them with a glass of cooled broth. Bring the strained broth to a gentle simmer, pour in the egg mixture, stir once and then leave it alone. Keep it on the lowest heat for 15–20 minutes — the white will gather into flakes on the surface. Strain through muslin.

Vegetables for flavouring the broth (onion, carrot, celery) go in whole 40–60 minutes before the end and then get thrown away — they've given their taste and become bland. Vegetables for the soup go in according to cooking time so everything is tender at once.

Onion and carrot cooked in oil for 7–10 minutes until golden give a soup depth. This isn't calories for their own sake: fat dissolves aromatic compounds that don't open up in water. Use 1 onion and 1 carrot per 2–2.5 l of soup and 2 tbsp oil.

Add 1 tbsp tomato paste to the sauté and cook it for 1–2 minutes — the sweetness deepens and the raw taste disappears.

Beetroot's red is the pigment betanin. It breaks down with long boiling and in alkaline conditions but is stable in acid. That's why the beet is stewed separately with acid and added at the end.

Grate 1–2 beetroots (300–400 g for 3 l of borscht) and stew them in oil for 10–15 minutes with 1 tbsp 9% vinegar or the juice of half a lemon and 1 tsp sugar. Add to the nearly finished borscht, bring to the boil and switch off at once. Let it stand for 20–30 minutes.

The base is vegetables cooked until completely soft plus a little liquid. Add the liquid gradually while blending: thinning a thick soup is easy, thickening a thin one is not.

For velvetiness you need fat: per 1 l of soup, 100 ml of 20% cream or 30 g butter stirred in at the end. For smoothness, push the soup through a sieve — that's the difference between homely and restaurant.

Fill a jug blender no more than a third full with hot soup and hold the lid down with a towel: steam expands suddenly and can blow the lid off.

A typical amount is 1 tsp (6–7 g) of salt per litre of soup, but salt at the end and taste: broth reduces, and sausage, cheese or sauerkraut bring their own salt.

If a soup tastes flat but has enough salt, it's missing acid. A teaspoon of lemon juice or vinegar for the whole pot brightens it. Soup is better the next day, once the flavours have married.