Grate zucchini, parsnip, and onion in a food processor. Remove any large un-grated pieces and chop finely. Transfer into a large bowl.
Add kosher salt, pepper, arrowroot starch, white rice flour. Stir well to combine.
Add sparkling water and mix again until mixture feels mushy.
Set a heavy bottomed stainless steel (for even heat) saute pan on high heat.
Add about 1/2 inch high of oil to the pan.
Note: To get your latkes crispy – without being greasy - heat your oil to 350 degrees F using a candy thermometer or wait until the oil appears thin and watery.
Add a piece of grated vegetable to the hot oil, if it sizzles immediately (rising up) then it’s ready for frying
Grab a handful of the mixture and squeeze liquid between your hands as you squeeze into a ball like shape.
Do not press down at this point because it could fall apart. It will flatten when you flip it over.
Cook about 3-4 minutes, or until dark golden brown
Flip over and cook another 3-4 minutes or until dark golden brown
Preheat oven to 350 degrees F, if serving the same day.
Transfer onto a stainless steel cooling rack (an oven safe cooling rack) set over a baking sheet.
If your cooling rack is not oven safe, transfer onto parchment lined baking sheet instead.
These taste great made up to 3 days in advance, stored in an airtight container
For making ahead/freezing:
Cool completely on cooling rack
Then put into a freezer safe airtight container with a layer of parchment or waxed paper between layers and freeze.
When ready, defrost few hours before and bake for 10 minutes