1. Center a rack in oven and heat to 200 degrees. Line a baking sheet with paper towels; set aside.
2. Using the large holes of a box grater or a food processor fitted with the grater attachment, grate onion, then transfer to a large bowl. Add eggs, matzo meal, parsley, 2 teaspoons salt, and 1/2 teaspoon pepper and mix until blended; set aside.
3. Fill a second large bowl with cold water. Shred potatoes, transferring shreds to water as you go. Remove one-third of shreds from bowl, shaking off excess water, and place on a clean kitchen towel (reserve soaking water). Gather ends, then twist towel over sink to wring out liquid; transfer shreds to bowl with onion mixture. Repeat with remaining potatoes, reserving soaking water in bowl and letting starches settle on bottom.
4. Mix potato-onion mixture well to combine. Slowly pour off and discard reserved soaking water until only starch remains in bowl; add starch to potato mixture and mix well.
5. Add enough oil to cover bottom of a large nonstick skillet by 1/4" and heat over medium-high heat until shimmering. Working in batches, drop 1/4-cup portions of latke mixture into oil, pressing each with a heatproof spatula to a 1/4" thickness.
6. Cook, flipping once, until browned and crisp, about 5 minutes per side. Transfer latkes to prepared baking sheet, sprinkle lightly with salt, and place in oven to keep warm. Repeat with remaining latke mixture, stirring if mixture separates and adding extra oil to skillet as needed. Serve warm with assorted toppings, if desired.
Source: Hannaford fresh Magazine, December 2019