Rinse rice until water runs clear then cover it with about 1L/1000g water. To that add 10g of salt, stir and allow to brine for 1 hour.
Drain off salty water. Heat a large heavy bottomed pot of water until it comes to a boil. Crush saffron into a powder with a mortar and pestle. Add in about ½ cup or 100g of the boiling water into the mortar with the saffron powder to bloom it for about 3 minutes.
Salt the boiling water generously then add in brined rice and boil for 3 minutes. Drain off the water and transfer rice to a bowl. Fold in saffron water.
Heat a nonstick pan (with a lid) over medium heat. Add a generous amount of olive oil, about 1-2tbsp, and 75g of butter. Once melted, add in all of the saffron rice, pressing down and spreading into an even layer. Dock the rice with the end of a wooden spoon about 10 times.
Wrap the lid of the pan with a kitchen towel then place towel-wrapped lid on the pan. Lower the heat to low and cook for 25-30 minutes, rotating the pan regularly for even browning.
When done, the rice should smell toasty and you should see some light browning around the edges. Flip onto a plate so that the brown bottom becomes the top.