Begin by peeling and grating the russet potatoes and onion using a box grater or food processor. Squeeze out excess moisture using a clean kitchen towel.

In a large mixing bowl, combine the squeezed potato and onion mixture with flour or matzo meal, baking powder, sea salt, and black pepper. Add the egg and mix gently until just combined.

Heat the vegetable oil in a heavy skillet over medium-high heat for about 5 minutes until hot but not smoking.

Using a tablespoon or small ice cream scoop, form the latke batter into discs and place them in the hot oil, ensuring there's space between each.

Fry each latke for 3-4 minutes on one side until golden brown, then flip and cook the other side for another 3-4 minutes.

Transfer cooked latkes to a paper towel-lined plate to drain excess oil. Sprinkle with kosher salt while still hot.

Serve immediately with toppings like sour cream or applesauce.