Today was the launch of my book, The Book of Burger and it put me in a burger mood, so I made the Blue-Rugula Burgers for dinner. The appetizer was stracciatella, which is Roman-style egg drop soup.
Stracciatella: To make about 8 cups of soup, you beat together 6 large eggs with some EVOO, a couple handfuls of Parmigiano-Reggiano cheese, some finely chopped parsley, and black pepper (I like lots). You bring 8 cups of chicken stock to a simmer and then you stir the egg mixture into the broth and keep stirring it until it looks like rags running through the soup. You can add a little spring garlic or finely chopped white and greens of spring onions to that as well. I throw a little extra parsley from the garden in the soup as well.
John and I prefer creamy Gorgonzola dolce for these burgers, but that can be tricky to find in a supermarket, so use Cambozola blue instead.
- 3 tablespoons butter
- 1 tablespoon EVOO
- 2 onions, thinly sliced
- Kosher salt and pepper
- 1/2 teaspoon ground thyme
- 1 bay leaf
- 1/2 cup beef stock
- 1 tablespoon light brown sugar
- 1 tablespoon good-quality balsamic vinegar
- 1 1/2 pounds ground beef chuck
- 2 cloves garlic, grated or finely chopped
- 2 tablespoons Worcestershire sauce
- A handful of fresh flat-leaf parsley, finely chopped
- EVOO, for drizzling
- 1⁄2 pound Cambozola blue cheese, thinly sliced
- 4 brioche rolls, split and lightly toasted
- Arugula leaves, coarsely chopped
Make the onions: In a large skillet, heat the butter and EVOO (1 turn of the pan) over medium heat. Add the onions, season with salt and pepper, and add the thyme and bay leaf. Cook, stirring occasionally, until the onions are caramelized, about 30 minutes. Add the stock, brown sugar, and vinegar and stir until the sugar is dissolved. Keep warm over low heat; remove the bay leaf before serving.
Make the burgers: In a large bowl, combine the beef, garlic, Worcestershire, and parsley; season with salt and pepper and mix thoroughly. Score the mixture into 4 equal portions and form them into patties slightly thinner at the center than at the edges for even cooking and to ensure a flat surface (burgers plump as they cook). Drizzle the patties with EVOO.
Heat a large nonstick skillet over medium-high heat. Cook the burgers for 10 minutes for medium, flipping once (adjust the cooking time for rarer or more well-done burgers). Top the burgers with cheese for the last minute or two of cooking, tenting the skillet with aluminum foil to help melt the cheese, if you like.
Place the burgers on the roll bottoms, mound with caramelized onions, and top with some arugula. Set the roll tops in place.