Peel and prep the sweet potato, carrot, and parsnip prior to grating.
Cut an onion in half and grate ¼ cup of onion and add to a mesh sieve (strainer) to drain excess liquid.
Using a box grater, grate the sweet potato, carrot, and parsnip. Add to a bowl with the onion.
To the bowl of grated vegetables, add the flour, whisked egg, salt, and coriander. Mix well using a sturdy spatula until the egg and the flour are well distributed and absorbed.
Preheat a medium sized cast iron skillet on a medium with oil. Use a large cookie scoop to scoop latke mixture and dispense directly into the hot oil.
Cook on the first side for 3-4 minutes or until the underside is golden brown. Flip, then cook until golden brown on the second side. Repeat until all the latke mixture is fried.
Notes
Be sure to watch the underside of the latke so that it doesn’t burn. Sweet potato and carrot will burn a little quicker than a traditional potato latke due to the natural sugars in them.Use just enough oil to coat the bottom of the pan and for the oil to come up just a touch on the side of the pan. I'd recommend starting with ½ cup of oil and add in more as you deem necessary.A cast iron pan is the best type of pan to use for frying latkes. Cast iron heats evenly and doesn't stick.Let the latkes sit on a cooling rack for a few minutes to crisp and cool before serving so that they don’t fall apart.