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Is there a biological reason why some vegetables are "good" to fry on a pan while some others are not?

  • I would readily fry onions (from "a little bit" up to "brown" or "caramelized"), leek (but just "a little bit" - the "brown" version is bitter), tomatoes, ...

  • I would not fry salad lettuce for instance.

I understand that there may be cultural differences, I am looking for a quantifiable reason (if there is one), such as "the more XXX in the vegetable, the more suitable it is for frying")

WoJ
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  • related/partial duplicate: https://cooking.stackexchange.com/questions/45901/why-is-lettuce-rarely-cooked – Cascabel May 21 '17 at 19:36
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    I am a bit surprised by the premisse of this question. Going through the (list of vegetables on Wikipedia)[https://en.wikipedia.org/wiki/List_of_vegetables] and excluding those I have never tried (WTF is catsear) I see only two I wouldn't fry, and these two are the ones I would never subject to any thermal treatment: lettuce and cucumber. But I have seen both cooked in restaurants, so this must be simply me staying true to a tradition. So, are you sure that some vegetables are really worse than others when fried? How do you define a vegetable as "good' or "bad" for frying? – rumtscho May 21 '17 at 20:49
  • There is not a single salad ingredient I can think of that would be ruined or unpalatable fried or cooked. In many Asian countries, vegetables are almost never eaten uncooked. With lettuce, it depends on varieties, some like iceberg lettuce are routinely cooked (fried and "water-fried"). Cucumbers are also routinely fried, either diced or in big chunks. Both are in fact common. – user110084 May 21 '17 at 22:47
  • The more suitable a vegetable is for eating uncooked, the less likely it will be eaten fried on any single occasion? Lettuce & salad greens are commonly fine to eat raw, so finding those vegetables cooked is rarer (than if not-fine to eat raw) and finding them fried is rarer still (as a subset of cooked). – Megha May 22 '17 at 02:31
  • Note that in some European languages *salad* also means lettuce or similar. I don't know where the OP is from but it might be worth bearing in mind when reading the Q. – Chris H May 22 '17 at 06:38
  • @rumtscho I imagine frying cucumber would be rather like frying courgette (OK if you don't let too much water escape; too slow and it goes mushy). Plenty of recipes for roast lettuce too. – Chris H May 22 '17 at 06:41
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    @ChrisH: I am from France, so "salad" indeed means "lettuce" in my head. I will update the question. – WoJ May 22 '17 at 07:14
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    I think this is just cultural therefore opinion based; the same way some would argue that fish needs to be cooked while others eat raw sushi. – Luciano May 22 '17 at 10:12
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    It kinda depends how you look at it: if the question asks, "here are things I'd fry and things I wouldn't, is there an underlying pattern?" then that can maybe be objectively answered, but if the question asks, "what things are good fried?" then it's subjective/cultural. – Cascabel May 23 '17 at 00:33
  • Lettuce can certainly be cooked, even in France. It's more common to “braise” it than “fry” it but there is nothing against that either (cf. also *petit pois à la française*). – Relaxed May 23 '17 at 08:01
  • @Relaxed: ha. So many years and so little knowledge. I learned something today (and will try the recipe). Thanks! – WoJ May 23 '17 at 08:09
  • @Jefromi: I will think about a better title. The last part of my question actually asks for the quantifiable reason. – WoJ May 23 '17 at 08:10

1 Answers1

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Stir-frying a vegetable is quite different (in my mind) than what's viewed as frying by American and British standards. I can't really speak for what's considered 'fried' in most parts of Europe since I've never been there to truly sample different 'European' foods - which varies greatly anyways.

Stir-frying in the Asian sense of the method means quickly and briefly (from 30 seconds to perhaps a minute) cooking smaller pieces of cut vegetables by stirring in a small amount of oil over very high heat. Oil with a high smoke point temperature is preferred. Peanut oil smokes around 450° F (230° C) which is why it's used more often though there are some fats with higher smoke points. After this brief exposure to very high heat, some liquid is added and a lid put on for a couple minutes more cooking but with a drop in the temperature to just under 212° F (100° C). To mY mind, that's not what people refer to as frying.

In the Western sense of frying, usually a lot more oil/fat is used. The temperature isn't as high since the food will only be cooking by frying, not a combination of methods. Plus the food is cooked for a longer period of time. It also depends on what kind of frying you're meaning. Shallow frying (pan frying) or deep frying? When you fried tomatoes, if they were ripe, I'd consider that more similar to stewing than frying.

I've stir-fried larger cubed pieces of cucumber and julienned white radish (daikon). I've briefly stir-fried quartered medium sized tomatoes when making Cantonese tomato beef. But with those vegetables, the high temperature and hot oil barely sears the outside of the pieces and only a little. Now imagine frying them Western style. They'd be limp and soggy. They'd release their juices as well. (Think what happens when you try to sauté too many mushrooms at one time - which I've done.) The results would be more like boiling with the addition of fats. Unappetizing!

Vegetables that are normally fried Western style seem to be those that are starchy (such as potatoes or sweet potatoes) or have enough sugar and some protein in them that Maillard reaction occurs which adds to flavour (like onions).

There are any number of vegetables that don't contain enough starch to gelatinize or no browning occurs from Maillard reaction but they're still fried. In these cases, the vegetables are normally battered coated, then fried. If they maintain their structure during frying, I think the only hindrance to frying them is a person's taste. I've never heard of anyone frying beets or carrots but why not? Some vegetables like beets probably need some pre-cooking though.

So in answer to your question, I don't think it's only the water content of a vegetable but whether it has enough starch to gelatinize when fried or the needed combination of sugars and protein for Maillard reaction. That precludes some vegetables like lettuce and cucumber.

Jude
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