Rinse the rice 2-3 times and then soak in water for a least 2-3 hours. (may soak longer, even overnight)
Bring a large pot of salted water to a full boil.
Drain and add rice to boiling water. Cook for 5-7 minutes or until almost done or al dente.
Drain rice and rinse with cold water to stop the cooking process.
Mix one cup of the rice with an egg yolk.
In a non-stick pot melt the butter, oil and turmeric (or saffron water) on medium heat. (To create saffron water grind 1 pinch saffron with 1 small pinch sugar and add to 1/4 cup hot water).
If using potato and/or onion place in pot in a single layer. Add rice/egg mixture and pat down to form a solid layer.
Scoop remaining rice on top into a mound. If using saffron water, drizzle some on top of the mound to create some brightly colored rice grains.
Cover with a doubled over paper towel and secure with a tight fitting lid. Take care that the paper towel does not catch on fire.
Cook on medium for 3 minutes to help crisp the bottom.
Reduce heat to medium-low for 20 minutes. Check rice. If bottom not crisped increase heat for 3 minutes and recheck.
Scoop out the soft rice onto a serving dish.
Either carefully remove crispy layer with a spatula or invert pot over the serving dish to remove. Enjoy!