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Onions and mushrooms
3 tbsp. unsalted butter
6 large onions, sliced julienne
1 tsp. salt and pepper, to taste
4 tbsp. vegetable oil
1/2 lb. oyster mushrooms, cleaned, bottom stem removed
4 tbsp. butter
4 tbsp. flour
2 cups half-and-half
2 tbsp. white truffle oil
1/2 cup white Cheddar cheese
Salt, to taste
6 quarts water
1/2 cup white wine vinegar
2 tbsp. salt
8 English muffins, halved
2 cups fresh baby spinach
1 white truffle (optional)
For onions and mushrooms: Melt butter in a 4-quart saucepan. Turn on medium heat and add onions as soon as butter is melted. Season with salt and let cook while stirring frequently to prevent onions from burning. Continue to cook until onions are soft and caramel colored. Remove from heat. Add vegetable oil to a 12-inch sauté pan and turn on high. Once oil is hot, but not smoking, add mushrooms and fry for 1 minute without stirring. Then stir mushrooms, season with salt and pepper and cook for an additional 2 minutes. Strain off any excess liquid and set aside.
For Mornay sauce: Cook butter and flour on low heat to create a roux. (Cook until it is a light caramel color and smells a little bit nutty with no aroma of raw flour.) Whisk in half-and-half until smooth. Add truffle oil and cheese. Season with salt and store in a double boiler or thermos, which will keep it warm for an hour or so.
To poach eggs: Bring water, vinegar and salt to a low boil. Crack eggs individually into a small bowl to make sure there is no shell or broken yolk and then gently drop into poaching liquid. Cook until the whites are completely set and the yolks begin to thicken but are not hard, about 5 minutes. Take out eggs with a slotted spoon in order of putting in, for even cooking times. Serve immediately or store in room-temperature water for about 10 minutes.
To serve: Preheat oven to 350 degrees. Toast English muffins. On each muffin half, place 3 tbsp. of caramelized onions, about 15 leaves of spinach and 3 tbsp. of mushrooms. Bake for about 10 minutes. Remove from oven and place onto serving dishes. Place 1 poached egg on each muffin half and drizzle with Mornay sauce. Shave white truffle on top, if desired.