I just went throught that by accidently drinking a glass of Sprite at restruant the other day. I went out of Ketsis about 3 hour after and with very stricked eating (re-induction) was back in Ketosis in less than 24 hrs.

Three spoonful of potatos may not have been bad enought to set you out of Ketosis. Just eat re-induction foods for a day or two and you should be just fine.

Good Luck!