Bring some water (enough water to cover the rice) to a boil in a saucepan, add in the rice, and stir. 2. Reduce the heat, cover and simmer for 30- 40 minutes until the rice is softened.
3.. Heat the butter in a large saucepan over medium heat, add the onion and cook for 3-5 minutes until golden brown.
Add the mushrooms and celery, and cook for a further 2 minutes, stirring constantly.
Reduce the heat and stir in the flour, cook for a further 2-3 minutes, stirring constantly, until the mixture begins to bubble.
Gradually add the broth, increase the heat and bring to a boil, then keep it at a steady boil, while stirring for 1 minute.
Reduce heat and add the cooked rice, half and half, sherry, salt, white pepper, curry powder, dry mustard, paprika, and chervil. Stir together until fully mixed.
Simmer for 3-4 minutes until heated thoroughly.
Serve hot and garnish with parsley.