Peel and grate potatoes, then immediately place in a mixing bowl filled with warm water. Allow to sit for 10 minutes, then drain potatoes and re-cover with warm water, repeating the process a total of 3 times. You'll know you're done when there are very few bubbles at the top of the bowl.

Squeeze out excess moisture. Working in batches and using a large cheese cloth, kitchen towel, or even an old pillow case, squeeze out all excess moisture from potatoes. Place drained potatoes in a large mixing bowl.

Meanwhile, grate onions and ring out any excess water. Add onion to potatoes, along with most of the eggs (I'll begin by using ¾ of them, reserving the rest), matzo meal, Kosher salt, baking powder, and black pepper, then mix well. If mixture seems too dry, add more egg a little at a time.

Heat enough oil to fill a pan about ½”. When oil reaches 400°F (204°C), drop about 1-2 Tbsp of latke batter into pan, making sure not to crowd the pan. Use the back of a spoon to pat them down a bit (you want them thin!). Fry about 2-3 minutes per side, or until golden brown, then carefully turn and brown the other side for about 1-2 minutes.

Drain on paper towels, then serve! Transfer latkes to a paper towel-lined cooling rack and immediately season with a sprinkle of Kosher salt. Repeat process with remaining latke mixture. Serve immediately or keep warm on baking sheets in an oven heated to 250°F (121°C). Serve with homemade applesauce or sour cream.