Two things make or break this, and both are easy to skip. Heat the oiled pan in the oven before the batter goes in, and purée the onions instead of grating them.
The hot pan is what gives you a crust on the bottom rather than a soggy layer. The puréed onion is so you don’t bite into crunchy onion in the middle — grated won’t break down in time, even over two hours.
Five pounds of potatoes and up to two hours in the oven. This is a feed-a-crowd dish, not a weeknight one.
Preheat oven to 350F and line a tin with avocado oil. Heat up tin in oven while preparing the batter.
Peel potatoes and put them in a food processor with a grate blade that will shred the potatoes. Set aside in a bowl.
Peel onions and put these in the food processor until pureed completely (otherwise onions will be crunchy... trust me from experience!)
In the bowl with the grated potatoes, mix in the pureed onions, eggs, salt, pepper, and matzo meal.
Take out pan from the oven and add potato mixture.
Drizzle 1 tbsp oil on top of the mixture so top will turn golden brown.
Bake for 1.5-2 hours, keeping a close eye that it doesn't burn. Enjoy!
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