Place sugar, saffron and water in a small pot and bring to a boil. Remove from heat. Add the rosewater and mix well. Set the syrup aside.
Place the all-purpose flour and rice flour in a large pot. Toast over medium heat for 5-7 minutes, stirring frequently.
Then add the oil and mix well.
Stir constantly over medium heat.
Continue stirring until the color is brown and you feel the smelling of cooked flour (it will take a while, be patient! Just do not burn the flour, you have to stir constantly). Once the flour is ready, remove from the heat.
Add the syrup and stir very quickly until halva thickens (just be careful when you add the syrup, it will start to sizzle because the flour mixture is very hot).
Place Halva in a dish and flatten with the back of a spoon. Garnish with slivered pistachios.