Juice the fennel, apple, lemon and tomato. Transfer this to a blender with the garlic and salt, then blend on full speed.
Once the garlic has been blended in, add the dill and blend on a lower setting to break up the dill without blending it all into one colour, so the specks of green still show through. This will give a more attractive cracker in the end.
In a bowl, combine the blended mixture with the chia and let that sit for 30 minutes. It will thicken up as the chia seeds go much more gelatinous. It’s better to juice all the ingredients as we’ve done here and soak the chia, rather than just blend all the ingredients up, as you might do with flax crackers, because too much fibre in chia crackers will stop them from crisping up.
Spread this mixture as thinly as possible over two nonstick dehydrator sheets, covering the whole sheets.
Dehydrate for 4 hours at 115 degrees F and then remove the nonstick sheet, transferring to a cutting board. Cut the crackers to the desired shape and size, which is easier at this stage, now they have been drying for 4 hours.
Return the individual crackers to the dehydrator, just on a mesh sheet, and continue to dehydrate at 115 degrees F for 14 hours.
Store for up to a week in a sealed container. If they go a little soft, they can be crisped up again in the dehydrator at 115 degrees for a few hours.
Rocket (arugula) pesto
Grind all ingredients in a food processor, leaving it a little chunky.
Can be kept in a sealed container in the fridge for up to 4 days.