If you are flying to Europe then it's vice versa, T2 is flights to/from the US, T1 is all other flights, European flights don't leave from T1 directly, you check in and clear security at T1 then take a bus to an infield terminal.

Remember you have to clear customs on entry to Canada, assume that will take half an hour, then you need to be back at the airport and checked in before the cutoff at 9:55 (yes, the cutoff is two hours) so you have at most, 3 hours and a bit to work with, assuming no delays, if you take the bus/subway downtown that will take pretty much an hour each way, again assuming no delays. Leaving you just over an hour to find a restaurant, get a meal and turn around and get back on the subway. Yes it can be done but I personally wouldn't recommend it.

The restaurant situation at Pearson is pretty dismal unfortunately but I don't think you have much choice.