Toyomansi and Bistek

Toyomansi is my latest favourite sauce. It's a Filipino soy sauce with calamansi lime juice, a sourish soy with a citrus fragrance. I like it but having had fresh calamansi before, I have a suspicion some flavouring other than real calamansi is added but on the label flavouring is not listed. Toyomansi is available from most oriental supermarkets, quite cheap under £2 for a large bottle of 750ml.