|1/2 whole onion (dry, approx 16)|
|1/2 lbs russet potatoe (quartered)|
|1 large egg|
|1/4 cup peanut oil|
|2 tbls dry instant mashed potatoes|
|1/2 tsp kosher salt|
|6 grinds black pepper|
Grate the onion in the food processor. Put onion in mixing bowl.
Shred the potatoes in a food processor fitted with a grating disc with medium-sized holes. Remove and discard any large chunks. Immediately and thoroughly toss with the onion.
Line a smaller bowl with cheesecloth and fill with the potato-onion mixture. Twist into a ball and wring out as much of the liquid as possible, reserving the liquid. Let the extracted liquid sit undisturbed for 5 minutes to allow the starch to settle, then pour off the liquid so that only the starch remains.
Whisk the egg into the starch and set aside.
Add the peanut oil to a cast-iron skillet to measure 1/8 inch deep and heat over medium until shimmering. (Target 375 degrees F)
Place the potatoes in a large bowl, add the instant mashed potatoes, salt and pepper and combine using your hands. Stir in the egg mixture.
Drop a mounded tablespoon's worth of the potato mixture into the skillet and flatten firmly with the back of a spatula. Fry in batches of 4 until browned, flipping only once, 2 to 3 minutes per side, then remove to a rack set over a pan lined with paper towels. Season immediately with additional salt. Continue to add fat in between batches to maintain 1/8-inch depth.