Grandma's Potato Latkes

Name: Grandma's Potato Latkes
Prep time: 25 min
Cook time: 20 min
Total time: 45 min
Cuisine: Israeli
Ingredients: 4 medium russet potatoes (scrubbed and peeled); 1 medium onion (peeled); 2 teaspoons Diamond Crystal Kosher Salt (or 1 teaspoon Morton Kosher Salt or Sea Salt); 1/4 teaspoon baking soda; 1/3 cup matzo meal (or matzo ball mix); Black Pepper; 2 large eggs (plus more if needed | beaten); Neutral oil (for frying); Flaky salt (for topping); A handful freshly minced parsley or dill (optional); 1/2 cup applesauce (homemade or store-bought | recipe follows); 1/2 cup sour cream; 6 medium apples (about 3 pounds (such as Honey Crisp, Granny Smith, or Macintosh) | peeled, cored, and diced); 1 1/4 cups apple cider (plus more if needed); 1/4 cup brown sugar; 1/2 teaspoon ground cinnamon; A pinch salt