Could I sub olive oil for butter in a sauce that calls for 1T of each? Also, in same sauce, could I sub cornstarch for potato starch? It's the pork tenderloin recipe in NY Times 3/7/12.
I think you could substitute cornstarch for the potato starch without too much trouble. Same with the olive oil, but if it says butter I'd use butter, especially in such a minor quantity. The call for butter is probably to impart its' delicious flavour.