Line a colander with a clean tea towel
Grate the onion set aside in a large bowl
If you are using a food processor to grate the potatoes, cut them in half or so they are able to fit in the feed tube. Place them in a bowl of cold water until all are peeled and you’re ready to grate. I prefer a finer grate but you can use whichever side of the blade or box grater you prefer.
Start grating the potatoes and transfer them immediately to the lined colander keeping them covered until all potatoes are grated.
Gather the ends of the tea towel together and twist them to help you squeeze as much liquid as possible out of the potatoes.
Add potatoes, flour, baking powder, eggs, salt and pepper to the grated onions. With your hands mix well.
Place mixture in colander and place colander in the large bowl so any additional liquid can drain into the bowl.
Heat 1/4 cup of oil in a non stick pan on medium heat. Test a bit of potato to make sure oil is hot enough.Dollop approximately 2 tbsp of mixture for each latke. These will be appetizer sized, but you can make bigger ones if you prefer. When you see the edges starting to turn golden brown flip and flatten them with a spatula. When the a browned on both sides remove from pan and place on paper towel. Sprinkle them with kosher salt while their are hot. Repeat add more oil as needed. Latkes can be frozen. To reheat place on baking sheet in a flat layer and bake at 350 for 10 minutes or until crispy.