I used some caramelized onion in a beef stew, taking my cue from Nigella Express. Trouble is, it's turned out far to sweet. What can I do to reduce the sweetness?
Nigella uses caramelized onions (sometimes called onion marmalade) from a jar as a speedy shortcut in some recipes, such as Rapid Ragu and Lamb, Olive and Caramelized Onion Tagine (from Nigella Express). In the tagine the sweetness of the onions is balanced by the salty olives and in the ragu the sweetness is balanced by the acidity of the chopped tomatoes.
The onions are useful but you do need to remember that they are quite sweet and often the jarred onions, which are naturally quite sweet, contain other ingredients such as sugar or redcurrant jelly. So in future you may find it easier to use a small amount of caramelized onion at the beginning of the dish and stir in some extra at the end of the cooking time, if you feel the dish needs it. To correct the over-sweetness of your existing stew you can try adding a little lemon juice. We would do this carefully, one small squeeze at a time, tasting between each addition. A pinch or two of salt may also help, but again this needs to be done very carfully and taste between each addition.