TL;DR: The Qur'an and Sunnah didn't come with percentages, so rulings are based around the hadith:
It was narrated from 'Amir bin Sa'd, from his father, that:
The Prophet [SAW] forbade a small amount of whatever intoxicates in large amounts. [grade: hasan] (sunnah.com)
In this way, 0.5% was declared insufficient to render a drink an intoxicant in some fatawa (IslamToday.net, IslamWeb, DarulIfta), but not all fatawa agree (AskImam.org, Islam.ru).
In my answer to Haraam or Halal? - Coke and Pepsi contain 0.001% Alcohol, I surveyed online fatawa which were nearly unanimous in declaring: if a substance is incapable of intoxicating even in large quantities, then it is not haram (insofar as to being an intoxicant).
One example is Islam Q&A, who tend to be stricter than other fatawa, who write: "...if something is mixed with alcohol but the alcohol is a small amount and does not have any effect, then it is halaal..." [in the context of non-alcoholic beer].
We know intoxicants are haram from the Qur'an (2:219, 5:90-91). But importantly, this applies to the whole item, not its constituent parts. In the context of non-alcoholic beer, the research committee of IslamToday.net write:
Sheikh Salman al-Oadah astutely observed: "The percentage of alcohol mentioned has no effect on the ruling. The ruling applies to the drink itself taken as a whole and not to its composition."
For example, a person weighing a mere 54 kg (120 lbs) would have to consume at least twenty-three 330 ml bottles of non-alcoholic beer at 0.5% alcohol per volume... to even begin to feel intoxicated by the alcohol that it contains. ... Hence, there are no grounds to prohibit this drink. And Allah knows best.
This gives some percentage figure for those erring on the side of caution, which we should be: Leave that which makes you doubt for that which does not make you doubt. (sunnah.com).
Finally, if the condiment is an intoxicant, it's best to avoid it altogether, as per the hadith "Wine is cursed from ten angles..." (sunnah.com):
The Fataawa of the Permanent Committee reads, “If the beverage that contains a percentage of alcohol intoxicates in large quantities, then it is unlawful to consume any quantity of it, large or small. It is also deemed prohibited to sell or buy such a beverage and it is obligatory to dispose of it because it is considered khamr (intoxicant). However, if the consumption of a large amount of such a beverage does not intoxicate, then it is permissible to sell, buy, and consume it ...” (IslamWeb)