Frittata is an Italian-style open-faced omelet, cooked slowly on the stovetop then finished under the broiler. Although it is a simple, rustic dish, it takes some time and effort. But it pays off with rich, deep flavors and satisfying textures. The asparagus, eggs, cheese, tomatoes and olives are all rich in umami.
Wash and trim the asparagus.
Cut into ½ inch lengths.
Cook in boiling, salted water until al dente, 1½ to 2 minutes.
Drain and set aside uncovered.
Heat the olive oil on medium in an 8” nonstick fry pan with a heat-resistant handle.
Add the onions, shallots and salt and toss to coat.
Caramelize them by cooking them very slowly (they should barely sizzle), stirring occasionally, until deep golden brown, about 20 minutes.
Drain the onions and shallots thoroughly, leaving as much oil in the pan as you can.
Set aside to cool.
Thoroughly mix the cheese, tomato, olives, pepper and cooled onion and shallots into the beaten eggs.
Reheat the oil in the pan on medium.
When a drop of water tossed into the pan sizzles loudly, add the egg mixture, stirring briefly to distribute the fillings.
Turn burner to low and let the mixture cook slowly.
You should see just a few lazy bubbles popping up around the edges.
Cook undisturbed until the edges are cooked but the middle is still very liquid, about 8 minutes.
Put the pan under a medium broiler until the top of the frittata is golden brown, the edges are puffed up and the center is just set (the center will jiggle slightly but pops right back after you poke it), about 2 minutes.
Don’t overcook it! Loosen with a nonscratch spatula, if needed.
Move to a warmed platter and serve right away.