How to Make It
In a medium saucepan, combine the wine with the onion, carrot, thyme, parsley, bay leaf and garlic and bring to a boil. Simmer over moderately high heat until reduced by half, 12 to 15 minutes. Strain the wine through a fine sieve and return it to the saucepan; discard the vegetables and herbs.
In a small bowl, blend 4 tablespoons of the butter with the flour to form a paste. Bring the wine sauce to a boil and whisk in the flour paste. Simmer over moderate heat, whisking, until thickened, 2 minutes. Season the sauce with salt and pepper and keep warm.
In a large skillet, melt 2 tablespoons of the butter. Add the mushrooms and season with salt and pepper. Cook over moderately high heat, stirring occasionally, until tender and browned, about 7 minutes; transfer to a large plate. In the same skillet, melt the remaining 1 tablespoon of butter. Add the bacon and cook over moderately high heat, turning once, until browned but not crisp, about 3 minutes; transfer to the plate. Add the pearl onions to the skillet and season with salt and pepper. Cook over moderate heat, stirring occasionally, until tender and golden, about 5 minutes; transfer to the plate. Keep warm.
Bring a large, deep skillet of water to a simmer over moderate heat. Crack the eggs into a small bowl, one at a time, and carefully slide into the simmering water. Poach the eggs over moderate heat until the whites are set but the yolks are still slightly runny, about 4 minutes. Transfer the poached eggs to paper towels to drain.
Arrange the toasts on plates, set the eggs on top and spoon the red wine sauce over the eggs. Scatter the mushrooms, bacon and pearl onions around the plate, garnish with chervil sprigs and serve right away.