In a skillet sauté the sliced onion in the vegetable oil and 1 tablespoon butter. When the onion becomes a light gold color, add the cream, salt, pepper and the balsamic vinegar and stir thoroughly. Reduce the cream, then turn off the heat, allowing the sauce to cool for 1 to 2 minutes. Set aside.
Combine the chopped beef, the grated Parmigiano-Reggiano and the egg yolks. Mix very thoroughly, correct for salt and pepper and shape into 6 patties. Brown them in a pan with 2 tablespoons butter. Transfer to a warm platter pouring the sauce over the patties and serve.
Serves 4-6 |
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