Bolognese stewed onions with tomatoes (friggione)

Method

1. Peel and halve the onions and slice them as thinly as possible, ideally on a mandoline. Toss them in a bowl with the sugar and the coarse salt.
2. Leave the onions to macerate at room temperature for at least 2 hours; they will release plenty of juice. Meanwhile scald, peel and finely dice the tomatoes.
3. Put the onions with the juice they have released and the lard into a wide, heavy pan (the original recipe prescribes aluminium). Cook over very low heat for about 2 hours, stirring often with a wooden spoon so that they never catch, until soft and hazelnut-coloured.
   TipSweating and caramelising onionsOnions refuse to be hurried: rush them and they blacken, give them time and they turn golden and sweet.Why and howShow less

   Why

   Onions are mostly water, and until it has evaporated the surface of the slices can't get much above 100 °C: over gentle heat they simply soften, turn translucent and lose their sharp bite – that is sweating. Only once the water has gone do the sugars start reacting with amino acids in the Maillard reaction and caramelising on their own, producing a golden-brown colour and a sweet, deep flavour. Properly caramelised onions take roughly half an hour to an hour over low to medium heat, depending on the amount; over high heat the edges brown and burn before the centre has softened, and burnt onion turns bitter. A pinch of salt at the start draws water out of the cells by osmosis, so the onions release their juice and soften faster.

   How to do it

   1. To sweat onions, use gentle heat and a little fat, and stir until soft and translucent but not browned.
   2. Add a pinch of salt right at the start so the onions give up their water faster.
   3. For golden onions, allow half an hour or more, and raise the heat only once the water has evaporated.
   4. Dissolve the brown film on the bottom of the pan with a spoonful of water and stir it back in – it's flavour, not burning.
   5. Use a wide pan so the water has room to evaporate, and stir more often the darker the onions get.

   If it goes wrong

   Pick out a few burnt bits; if the whole batch tastes bitter, it can't be saved – neither sugar nor cream will reliably mask it, so start again over lower heat. Onions that won't colour are still wet: uncover the pan and let the water cook off.

   Full card

4. Add the tomatoes and cook for about 1.5 hours more, stirring constantly. The friggione is ready when the onions and tomatoes have become a thick cream and the lard forms pinkish bubbles on the surface. Serve warm with boiled meats (bollito misto).