Instructions

1. Leave the peel on the apple and only take out the core. The skin carries most of the pectin, and pectin is what stops a cracker built on fruit from crumbling as you lift it.
2. Use cooked sweet potato that has been mashed smooth and is properly cool. Warm mash starts to gel the flax on contact and you lose the working time.
3. Blend the apple chunks, sweet potato and sesame seeds into a smooth puree. The seeds want to go in at this stage rather than later — blended they release their oil through the whole mixture instead of sitting on the surface and toasting.
4. Fold the puree into the flaxseed base until there is no streaking. The base is the only binder here, so anywhere it is thin is where the sheet will break.
5. Spread half the mixture onto each of two lined trays, in a square of about 25.4 cm, and level it with a spatula. Run a straight edge round the outside: a ragged edge dries first and burns while the middle is still wet.
6. Give it 3 hours at 52 °C, which is enough for the top to firm up.
7. Take the trays out and score the sheets into 2.5 cm squares with a pizza wheel, cutting right through to the liner. Score now, while it gives — a finished sheet shatters instead of scoring.
8. Return the trays for a further 10 hours, flipping the sheets onto mesh once they hold together, so the undersides are not sitting against solid plastic for the whole run.
9. Let them cool completely before you break them apart along the score lines. Warm crackers bend; cold ones snap, and the snap is how you know they are done.
10. Store them airtight with a sheet of paper between layers. The sesame makes these oily, so a month is a fair expectation and rancid seed is what you will taste first.