One 30-ounce bag frozen shredded potatoes, defrosted (see Cook's Note)
2 sheets unsalted matzo (see Cook's Note)
1 medium red onion, quartered
3/4 teaspoon kosher salt
1/2 teaspoon ground black pepper
Vegetable oil, for deep-frying
Full-fat sour cream or unsweetened applesauce, for serving
Using individually quick fozen (IQF) packaged shredded potatoes eliminates most problems with moisture. Resist the temptation to substitute breadcrumbs for the matzo. They aren't the same, and the taste, texture and appearance will change greatly. The latke mixture will keep in the refrigerator for several days, but be prepared: you'll have to squeeze the latkes even harder to get the water out.