Peel and grate Russet potatoes. Rinse with cold water and drain, gently pressing to relieve excess moisture. Mix half the potatoes with the mashed potatoes. Pulse the other half of the grated potatoes with the onion in work bowl of food processor to form a coarse paste. Do not over work.

Combine the two mixtures, season with salt, pepper, eggs, and matzoh meal. If your mixture is too wet, add another tablespoon or so of matzoh meal—remember, you can always run a test batch. 

In a large skillet over medium heat,  heat enough vegetable oil to come up the sides of the pan 1/3 of an inch. When oil is 350 degrees, or a small pinch of batter instantly sizzles when dropped in, fry small 2- to 3-inch-sized patties in batches until golden brown on both sides. Drain on paper towel.