Preheat the oven to 450 degrees. When the oven is hot, pour two tablespoons of oil onto two jelly roll pans and turn them in every direction so that the oil coats the pans. Heat the pans in the oven for five minutes.

Place the onions and scallions in the bowl of a food processor and chop them into small pieces. Place them in a medium bowl. Shred the potatoes by hand on the large holes of a box grater or in a food processor with the shredding blade, and place in the bowl. Add the lemon juice, eggs, baking powder, potato starch, salt, and pepper and mix well.

Very carefully (I mean really carefully; move very slowly) remove one of the pans and use your hands or a spoon to scoop up and drop clumps of the potato mixture, a little less than 1/4 cup, onto the pan. I use my hands. Press the mixture down to flatten it a little.

Place the pan in the oven for 10 to 12 minutes and immediately remove the second oiled pan. Repeat the same process with the remaining potato mixture and bake the second pan of latkes for 10 to 12 minutes. Bake them until the edges are well browned, and then with a slotted spatula turn them over and cook the latkes for another eight to ten minutes, or until the bottoms are browned. May be made two days in advance and reheated in the oven.

Heat the oil in a small saucepan over medium heat. Add the onions and cook them for three minutes, until they soften. Add the vinegar and brown sugar and cook for another three minutes. Add the apples, coriander, ginger, cinnamon stick, salt, and pepper, and cook, covered, on low heat for 15 minutes, or until the apples are soft. Let the mixture cool for 10 minutes and then purée it, using an immersion blender or a food processor. May be made four days in advance and served warm or cold.