Interesting observation on the puree curdling.
I posted a little while ago asking "what is tomato puree". From the responses I got, I was using the right thing, but one of the reasons I felt compelled to ask was the curdling you mention.
Whenever I add it to the frying pan, I stir, squish, blend like heck but it most always ends up looking like frying gobs of tomato by the time I add the spices.
To compensate, I often use pasatta, which should give the same effect if I get the quantity right taking into account the concentration of the puree.
Guess its just the brands they sell here in Canada, but I've decided to just dilute a little with water, seems to help. I guess the BIR's use this "Tower Brand" for a reason.
-- Josh
-- Josh