Mixing horseradish into both the frittata and the sour cream topping gives this easy brunch dish lots of horseradish flavor. Combine whisked eggs with prepared horseradish and sharp cheddar cheese, then pour the mixture over sautéed asparagus and onions and bake until the frittata is puffed and browned. Cut it into wedges, drizzle with an easy horseradish and sour cream sauce, and sprinkle with fresh chives for an elegant breakfast option that’s also kosher for Passover.
What to buy: Asparagus spears can vary in length and thickness; for this recipe, the thinner 1/4-inch-thick spears work best.
1 tablespoon finely chopped Italian parsley leaves
1 teaspoonkosher salt, plus more for seasoning
1/2 teaspoon freshly ground black pepper, plus more for seasoning
Pinch freshly grated nutmeg
Finely chopped fresh chives, for serving
For the horseradish sour cream:
Whisk all of the ingredients together in a medium bowl until smooth. Cover and refrigerate until ready to serve.
For the frittata:
Heat the oven to 400°F and arrange a rack in the middle.
Heat the oil in a large oven-safe nonstick frying pan over medium heat until shimmering. Add the onion, season with salt and pepper, and cook, stirring occasionally, until softened and lightly browned, about 5 minutes. Add the asparagus, season with salt and pepper, and cook, stirring occasionally, until the asparagus is crisp-tender, about 5 to 6 minutes more.
Meanwhile whisk the eggs, milk, cheese, horseradish, parsley, measured salt and pepper, and nutmeg in a large bowl until evenly combined.
Turn off the heat, pour the egg mixture into the pan with the asparagus mixture, stir with a rubber spatula to combine, and spread the asparagus into an even layer. Transfer the pan to the oven and bake until the frittata is puffed and just set in the center, about 10 to 12 minutes. Remove the pan to a wire rack and let it cool slightly, about 5 minutes.
Loosen the edges of the frittata with a rubber spatula and slide it onto a cutting board. Slice it into wedges and serve immediately, passing the horseradish sour cream and chives on the side.