Poached eggs with buttered mushroom and brown sauce (Trứng trần kiểu Pháp với nấm xào bơ và sốt nâu)

Ingredients (serves 2):
- 4 small to medium fresh eggs
- 200g button mushrooms, thinly slice both the roots and caps
- 1/2 small yellow onion, thinly sliced
- 100g butter
- 1l water and 5 tbsp vinegar
- 100ml red wine
- 1/2 tbsp multi-purpose flour (or tapica flour or corn flour)
- Salt and pepper to taste

Procedure:
- Place water and vinegar in a non-sticky pot, heat until the water almost boils, keep the water on the lowest heat possible. Do not let the water to boil at all. Add 1 egg (maximum 2 eggs) at a time in the pot). Slant the pot a bit so that the egg white is well distributed around the egg yolk. Let the water simmer but not boil. Cover the pot, turn off the fire. Keep for 3-5 minutes.
- At the same time, sweat sliced mushrooms with 50g butter for 5 to 10 minutes. Add salt to taste. Serve cooked mushrooms on 2 separate plates, keep the sauce in a bowl.
- Mix the sauce (of around 100ml) with 100ml red wine and 1/2 tbsp flour. Stir-fry sliced onions with 30ml butter, then add the sauce mixture and cook over low heat till the sauce reaches thickness. Add salt and pepper to taste.
- Take out and place the eggs over mushrooms. Leave 10g butter over the eggs on each plate. Pour the brown sauce with onions on top. Add fine black pepper and serve with butter-fried bread and boiled long bean with browned butter sauce.