Once in a while, particularly in hot summer evenings, I get an overwhelming hankering for anything acidic, preferably a drink. It’s probably related to sweating a lot and losing electrolytes. Annoyingly, since my fridge is stocked sparingly and I don’t typically consume fizzy drinks, I have to resort to munching on whatever is there: pickle juice if I’m lucky, or straight up diluting citric acid or vinegar if I’m not.

Regarding your situation: soy sauce is pretty much prescribed to you. Try also Worcestershire sauce, you’ll only need a few drops of it — goes well with leafy salads. But don’t go for cheap varieties, or it’ll be mostly vinegar: get Lea & Perrins, Henderson’s, maybe Heinz (but the latter seem to generally lean on vinegar lately).

Look also into relishes/sauces/stews/preserves made with sauteed vegetables, popular in South and Eastern Europe: e.g. lecho, ratatouille, ajvar, lyutenitsa, sataraš, peperonata, piperade. Particularly preserves made with variously prepared eggplant, like pindjur; or with roasted beans. If you’re lucky, something like this might be sold in supermarkets where you are. These dishes are typically quite savory.