Set a large strainer over a bowl. In a food processor fitted with the shredding disk, shred the potatoes and onion in batches. Add each batch to the strainer and let stand for 5 minutes, then squeeze dry. Pour off all of the liquid in the bowl and add the shredded potatoes. Stir in the flour, eggs, dill, salt and baking powder. Scrape the mixture back into the strainer and set it over a bowl; let stand for 5 minutes.