Preheat oven to 400 degrees. In a food processor, fine-grate potatoes (don't liquefy; leave some texture), and strain to eliminate excess liquid. Don't overdo it; just let the water drain out. Fine-grate onions, and mix in a large bowl with potatoes. (If you don't have a food processor you can grind the potatoes and onions in a meat grinder.)
Add eggs, baking powder, 3/4 cup corn oil (most of it cooks out), flour, salt, and pepper; mix well. Fold in matzo meal, making sure that everything is very well blended.
Heat 1/2 cup corn oil in a deep skillet. Spoon batter (use a large kitchen spoon) into the pan to create pancakes about 3 1/2 inches in diameter. Fry on low heat for 3 to 4 minutes until underside is a deep golden brown turn, and fry for another minute or two. Drain on paper towel. Serve with applesauce and/or sour cream.