Spices and using "find it" games with food
A few years ago I spoke with the feline keeper at Woodland Park Zoo. This may be of more general interest. She said they regularly feed their cats spinach and lettuce. They hang up leaves for their sampling. In addition, they fast their cats one day out of ten, and offer them spices such as nutmeg, sage, and cinammon.
Max the Serval goes absolutely *bonkers* over cinammon. We sprinkle it on an old dish towel and he will roll around with it and drool for half and hour. The only food he will actually fight you for other than broccoli is cinammon toast.