When you did your research did you uncover Taco Bell closed down on the Polish market some years ago?
Yes, but that was because they hadn't thought through their supply chain, which resulted in them doing insane things such as having their crispy tacos imported by air from the USA.
A very nice TexMex lunch place in Zloty Taras closed down
That was due to structural problems with the building itself, not due to the actual place itself not making any money.
There's a decent one on Senatorska, just round the corner from the Wierzbowa restaurant run, but not cheap and in very good (and presumably expensive) premises.
Is it actually decent food? I've not been there for several years.
Personally I love the tex-mex at Spoco Loco. They have two places already and are now franchising
There's also place in the building at Jerozolimski 123 called Dos Tacos which I haven't been to but is Mexican owned and run and gets very good reviews, apparently it's where the staff from the Mexican embassy eat