Purebred or not?

[Casper]

Sala, our newest addition, was said to be a Lhasa Apso.
She is around 11" tall at the shoulders and 19 lbs (Psst...don't tell her, but she is a bit on the chubby side).
My sister swears Sal is not purebred.
To be frank, I am not too familiar with purebred dogs, and I have never seen a Lhasa in person.

Anyway, I just wanted some opinions. It does not matter to me if she is a mutt or 100% Lhasa, she will always be my favorite little ball of fluff. One can't help but be curious, though. ;-)

Thanks for your opinions!