Possible substitue for vinegar

Unfortunately there really isn't anything that tastes like vinegar except for vinegar, and the lemon juice you're trying is about as close as you're going to get.

It just comes down to chemistry. Most categories of edible compounds, like starch, protein, hydrocarbon lipids, etc. have a ton of different compounds in them, so if you have to avoid one you can often find another with very similar characteristics regarding flavor and how it reacts with other compounds when being cooked. These chemical similarities are what allow for good substitutions.

The problem is that vinegar comes from the much less human-friendly compound category of acids. The list of edible acids is incredibly short, and once you rule out the ones you either can't use (carbonic only exists in carbonated drinks) or wouldn't ever want to put in your mouth (butyric and lactic come from spoiled dairy products), you only have a handful of possibilities. The food acids you're left with at this point are:

• oleic (olive oil)
• palmitic (palm oil)
• oxalic (tomato)
• tartaric (tamarind)
• citric (citrus obviously)
• acetic (the vinegar you're trying to get away from)

The only thing on that list that even remotely shares vinegar's tanginess is citric acid, which is why lemon juice is the standard suggestion to use in a pinch if one is out of vinegar.

Your best bet would be to experiment with other citrus juices and see if perhaps using something other than lemon would help things taste better.

Citrus juice is probably the most widely available substitute. However, if you can get your hands on some Verjus (or Verjuice) you will be pleasantly surprised.

Verjus is the juice of pressed green grapes. It is similar to wine but the grapes haven't had a chance to ripen and there isn't any alcohol. It has a much more neutral flavor than lemon juice. It can be difficult to find though. I buy mine at a local vineyard. You may be able to find some online.

https://en.wikipedia.org/wiki/Verjuice

I have been allergic to vinegar for years, I cook frequently and have not found a substitute for most condiments because as a couple of you noted- citric acid usually tastes bad, and nothing tastes like vinegar.

A few tips:
Coleman’s mustard doesn’t have vinegar! Make your own hot sauce by boiling and pureeing habenaros (wear a mask). Make your own mayo with lemon juice. Homemade hollandaise is also vinegar free when lemon is used

Citric acid powder or granules, as opposed to lemon juice. This will impart less undesired flavor than lemon juice, should be a better substitute. 1/4 teaspoon substitutes for 2 tablespoons of 5% vinegar, or 1 tablespoon lemon juice. I got mine from Amazon.

I find rhubarb juice home made is fabulous in oil and “ vinegar” salad dressing. I can’t eat vinegar or alcohol or citrus. Didn’t know about ascorbic acid.

Rhubarb juice rocks it and there is a lovely pink color

I also can’t tolerate vinegar due to inflammatory actions. I also can’t tolerate ascorbic acid or citric acid. To compensate I found a chefs tip that I tried for a suitable substitute. I Add 1 part Amchoor or Amchor powder with two parts water, mixed and refrigerated overnight to allow the two to meld & produce a nice tart substitute that I can use in place of vinegar in cooking and salad dressing. It’s not acidic so it’s not a preservative. Amchoor or Amchur. Powder is dehydrated green mangos. I hope maybe this might help you.

Brew your own wine stores sell "acid blend" crystals which include all three of the main organic acids: tartaric, malic, and citric. The ratios differ between brands. You could try mixing up a bit of acid blend in water to make a solution that is 5% acid, similar to the acid level in vinegar and see how you like it.

Some wine shops also sell the acids separately which would allow you to adjust the ratios to your own liking. Most fruits are a combo of malic and citric acid, so if it were me, I would make a 65:35 blend of malic and citric and leave out the tartaric, as tartaric acid is pretty rare in nature. Malic acid is a good flavour blender, and its sourness lasts longer. Citric acid is sharper, fresher, and quicker.

In situations where you want a lot of citric acid character one of the citrus fruits will give you more complex flavor. Limes have the strongest flavour, lemons are a bit less strong, but oranges are fairly mild and tend not to dominate. Orange flavoured bitters are handy in cooking.

A solution made with a 50:50 blend of tartaric and malic acid could stand in as a replacement for wine vinegar. One made with just malic acid could stand in for apple cider vinegar.