Onion soup 17th century

Here's the simplified version:

### Onion Soup with Egg Yolk and Lemon

**Ingredients:**
- 1 large onion, sliced
- 1 tbsp butter
- 1 tsp flour
- 1 cup water
- 1 slice bread, cubed
- 1 egg yolk
- 1/2 tbsp lemon juice
- Salt and pepper

**Instructions:**
1. Sauté onion in butter until golden (10-15 min).
2. Add flour, cook 1-2 min.
3. Add water and bread, simmer 5-10 min.
4. Whisk egg yolk and lemon juice, slowly stir into soup.
5. Season with salt and pepper, serve hot.

Enjoy!