Matzo Brei with Caramelized Onions

“Why are you making fried cardboard?” my first husband asked the first time he watched me make matzo brei. He had never before encountered this classic Jewish dish. Then he tasted it, his eyes went wide, and he asked for more.I have never known anyone who could resist it; even my son, the world’s pickiest eater at the age of two, was in love with it. As for me, if I could eat only one food for the rest of my life it would be this remarkably simple dish in which a few basic ingredients are magically transformed into something comforting and compelling.Rumors are floating about that there are people who like their matzo brei sweet. This, of course, is an abomination: Matzo brei should never mix with sugar. While I tend to be a purist—nothing but matzos, eggs, butter, and salt—I occasionally add caramelized onions which, in my opinion, make almost everything taste better.And now, on to my matzo brei rules:1. Do not use those fancy new handmade matzos. Store-bought is fine.2. Caramelize the onions slowly and for a very long time. You want them to be on the dark side.3. Good butter is the secret to great matzo brei.4. When in doubt, use more.5. Break the matzos into a strainer set over a bowl so you catch all the tiny crumbs. They make the texture more interesting.6. Don’t get your matzos so wet they go limp.7. Some people cook their matzo brei in one piece, as if it were an omelet. Don’t. One of the great things about this dish is the textural variation: Some bits are fluffy as clouds, others crisp enough to crackle.8. Do not use a nonstick pan because it will prevent you from achieving the results in rule 7.9. This recipe serves 4, but the proportions are 1 egg and 1 matzo per person, so adjust to your needs.10. Say the word right: “brei” rhymes with “fry.”