What foods we eat and how much is dependent on the length of your fast. Fasts below 7 days can be broken with any organic fruits or vegetables, longer fasts should be broken with some organic fruit juices.
Your question about flaxseed is fascinating. IMO, all nuts and seeds should be consumed after one weak of fruits and veggie diet after recommencement of eating. Flaxseed does have good amount of fats, but you are not going to eat 1 cup full flaxseed in one seating. Actually flaxseed with each meal will be a great nutritive food once regular eating is resumed.