Add the peeled shrimp or prawns to a food processor. Process until you have achieved a fine paste.
Add in the tapioca flour, and continue to process until the mixture comes together into a thick dough.
Add the salt and any other spices or herbs that you want to add. Adding cayenne pepper will give spicier prawn crackers. If you want the crackers to puff up more when deep-frying them, add in a little baking powder. Process again until all of the ingredients are well incorporated into the dough.
Check the consistency of the dough to see if it can be formed into a roll shape. If it is too dry, add a bit of water. If it is too wet, add more tapioca flour.
Knead the dough until it is smooth, adding more flour or water as needed.
Shape the dough into two log-shaped rolls that will fit into your steamer. Place the rolls in a steamer. Consider lining it with banana leaves or parchment paper first to keep them from sticking.
Steam the dough rolls
Steam the dough rolls for about an hour. You will notice that the color and texture of your rolls will change quite a bit throughout the steaming process. Add more water, as needed.
Remove the dough rolls from the steamer, and let them cool. They should now have a rubbery texture.
Cut thin slices from the rolls of dough. You can use a sharp knife or a food processor.
Slice the dough into disks
Dry the slices using the sun, a dehydrator, or an oven at the lowest heat setting. If sun-drying the crackers, cover them with netting to keep insects away. They may curl up a little. You can flip them halfway through to get them to dry more evenly. They should dry up into hard little disks.
Make sure the prawn crackers are fully dried. Dry crackers will no longer be flexible and will break when bent.
Deep fry the crackers
Once completely dry, you can deep fry the prawn crackers. Use enough oil so that your crackers can be submerged in the oil completely. To achieve the right temperature (around 360ºF/180ºC), wait until a small piece of cracker sinks down in the oil and then immediately floats up to the surface and begins to expand. You may have to press down on the crackers to submerge them completely in the oil. If they aren't fully submerged, they may not expand completely, leaving dry, hard, un-fried areas.
Once the crackers have puffed up, remove them from the oil. (A strainer can help drain the oil off.) Place the crackers on plates that have been covered with cloth or paper towels to help absorb any excess oil.
Serve immediately, and enjoy!
Be careful if using a food processor to slice the rubbery dough. It may break the machine if the dough gets stuck between the disk and the lid and you aren't quick to turn it off. The remaining dried prawn cracker slices, if well dehydrated, can be stored in a well-sealed container in a cool, dry place for several months, until you are ready to deep-fry them.Prawn crackers can also be cooked in the microwave. A microwave won't give the same results as deep-frying, but it will allow them to puff up and be cooked. Nutritional information is an estimate based on cutting 80 crackers from the dough and eating 5 of them. It doesn't include the oil used for deep-frying.