How to Make the Ultimate Umami-Bomb Vegetarian Demi-Glace
1 quart water
1 cup polenta
2 tablespoons unsalted butter, plus more for frying
1/2 cup (1 1/2 ounces) freshly grated Parmigiano-Reggiano cheese
Salt and freshly ground pepper
Olive oil for frying
Lightly oil a 6-by-10-inch glass or ceramic dish, 3 cups.
Bring the water to a boil in a large saucepan. Slowly whisk in the polenta. Cover and cook over low heat, whisking often, until thickened, about 10 minutes.
Stir in the butter and cheese, season with salt and pepper and, while hot, pour into the dish. Let stand until room temperature and firm, about 30 minutes. Cover with plastic wrap and refrigerate overnight.
Cut the polenta into 1-inch-thick slices. In a large non-stick skillet, melt butter in olive oil. Fry the polenta slices over moderate heat until golden brown and crisp, about 8 minutes per side.