I believe you can break a fast on almost anything, and I've done so on several occasions.
The key is in the amount of solid matter you eat. It has to be very very little food. Your body should have no problems.
That being said, juices are easiest, as was mentioned. Vegetable juices do not have as much sugar, which is probably a good thing. tomatoes and carrots are easy to juice.
If you continue on juice for a week or so, you will slowly turn your digestive system on, but you will also continue healing as you do so and with much more energy.