Potatoes and corn, losing though would be absolutely tragic. Also avocados.
Compare that to pork for instance. Remove that and you've removed like 50% of Austrian cuisine.
They couldn't find one mammal from which to obtain milk? It's a pretty obvious thing to try, for obvious reasons.
I guess that lactose-intolerent people today would drink milk rather than starve - do they get zero nutrients from it? - and that evolution would select for those who could survive that way.