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Onions, Sliced and Fried
Onions, cut into thin slices, fried in a little hot butter until they are browned, without being burnt, then mixed with flour, and afterwards pressed through a fine sieve, are excellent for flavouring and colouring brown soups and sauces.
This is a component rather than a dish: a browned onion purée thickened with flour, kept on hand to give brown soups and sauces both colour and depth. No quantities are given, which is normal for a principles section.
- Working quantitiesThe original gives none. As a starting point, two medium onions (about 8 oz) to 1 oz butter and 1 tablespoon flour makes a small quantity of paste; use it to taste, since how far it goes depends on how dark the onions are taken. Keep any surplus covered and refrigerated, and use it up within a few days.
- The hinge is the browningThe onions must reach deep mahogany without a single scorched edge. Burnt onion turns irreversibly bitter and a bitter paste will taint the whole pot, so keep the heat moderate and stir; 25 to 35 minutes is realistic, far longer than the brisk "fried in a little hot butter" suggests.
- Slice thin and evenThin, uniform slices brown at the same rate. Thick pieces stay raw in the centre while the thin ones carbonise, which is the usual cause of bitterness.
- Adding the flourThe original only says the onions are mixed with flour. Sprinkling it over the browned onions and letting it cook a couple of minutes before sieving helps avoid any floury edge in the finished sauce.
- Instead of the sieveSieving (or pounding and then sieving) was the usual way to get a smooth purée in a kitchen of this period. A blender or stick blender does it in seconds, though a sieve afterwards still catches the papery fragments if you want a glossy sauce.
- How it behaves in the potWhisk it into simmering liquid a spoonful at a time and let it cook five minutes so the flour swells. It thickens as well as colours, so allow for that before adding other thickening.
- Why not just use browningBottled gravy browning gives colour and nothing else. This gives the sweetness and body of caramelised onion, which is the point of the entry.
This belongs among the principles of cookery rather than the recipes because it belongs to the older kitchen's stock of colourings and flavourings — the same shelf as glaze, browned flour and burnt-sugar caramel, all kept ready so a cook could correct a pale sauce at short notice. Before commercial gravy browning and stock cubes were common, a brown soup or espagnole got its colour from work done in advance: bones roasted dark, flour toasted, onions taken to the edge of burning. The technique is essentially the sweating and browning of onions that underlies French brown sauce work, reduced here to a keepable paste for an English household kitchen, and it survives in the fried-onion pastes still sold for curries and in the browned onion base of many soups.