1
Shred potatoes, using coarse shredder blade of food processor. Transfer half the potatoes to a mesh sieve set over a medium bowl.
2
Change food processor to steel chopping blade. Add onions to potatoes and process until coarsely chopped (about 1/8" chunks), 5-6 one-second pulses.
3
Move potato-onion mixture to sieve and combine with shredded potato. Squeeze fistfuls of this mixture to remove as much liquid as possible; transfer to a dry bowl. Let remaining liquid sit in bowl until starch settles to bottom, then drain off the clear liquid, leaving the starch behind.
4
Beat eggs, salt and pepper into starch, then add dry potato-onion mixture and fold together thoroughly. Add matzo meal until mixture is stiff enough to form patties.
5
Pour oil into 12" saute pan until it is 1/4" deep and heat over medium-high heat until shimmering but not smoking. Take 1/4 cup of potato mixture, press into 1/2"-thick disc and place in oil; press gently with spatula. Repeat until there are 5 latkes in pan.
6
Adjust heat to keep edges of pancakes bubbling; fry until golden brown, about 3 minutes. Turn over and fry until golden brown all over, about 3 minutes more. Transfer to a triple layer of paper towels on a sheet pan. When oil is shimmering again, repeat. After every two batches, discard the oil and start over with fresh oil; continue this cycle until all the latkes are cooked.
7
Serve hot with sour cream or applesauce. Latkes may be cooled to room temperature and held up to four hours; to reheat place on a hot cookie sheet in a 375F oven for about 10 minutes, turning once, until hot and crisp. To freeze, place in a single layer on a cookie sheet and freeze until solid, then transfer to a zip-top freezer bag; reheat in a 375F oven until hot and crisp, about 8-10 minutes per side.