Question

You’ve said several times that you believe the Torah was given at Mount Sinai, but that you’re open to the idea that parts of it are later additions, although in any case it’s almost impossible to prove such (historical) claims with much certainty.

 I wonder: what would you regard as the most minimal Torah such that, if you became convinced it was not from Sinai, you would leave Judaism? Is it a certain percentage? Is it certain chapters or specific commandments that, once you think they are not from Sinai, would be a game changer? How do you see this?
What, in your view, is the core and essence of the Torah that must not be a later addition in order for it to retain divine authority?