The ingredient is a fruit that you find, somewhere close to home. You probably haven't reached to the point you can use the amulet yet, it's somewhere in the pyramid.
I can fight her again, but she don't drop another lemon, and if i fight her one more time, during the battle she is invisible (and you can't attack, you get stuck)
Be the way, i found a very useful glitch/easteregg, when you are in the space ship, if you click and hold on a planet, you will fly to it with berdy, when you release the button you will skip the meteour/asteroid part, is this a glitch? if so, please don't remove it, it's really useful :p