Even more surprising so many bad answers from some of the terrans too...
Vs that composition it is extremely tank heavy, but in general vs tanks heres a few tips
a> dont mass stalkers, they suck past earlygame, imho late on a 4-1 ratio of zealots to stalkers is best
b> dont go voids in general, any decent terran player has marines and you need masses of stalkers + voids to make a decent comp out of this, and well, considering how much stalkers suck.. we move onto
c> dont get immortals past early-mid period
Do what any decent protoss player should do and go zealot+templar+archon
Your biggest troubles come when he mixes hellions imho because it burns your only tank (zealot line) very easily