Put the potatoes and onions in a colander and sprinkle with the salt. Toss well and let sit for 5 minutes. Press out liquid with a paper towel and transfer to a large bowl.
Add the pepper, egg, flour, and baking powder and mix well.
Drop the mixture onto a parchment-lined baking sheet into 8 even latkes. Flatten with the back of a spoon.
Bake for 10 minutes, flip, and continue baking for 10-12 minutes more until well browned and crisp.