Pour boiling water over ground saffron; let sit for 30 minutes. Reserve 1/4 cup for rice; save remaining brewed saffron for another use.

Heat 2 tablespoons vegetable oil in a pan over medium-high heat. Saute onion until light brown, 5 to 7 minutes. Stir in ground beef, 1/2 teaspoon salt, black pepper, and turmeric. Cook and stir until beef is browned and crumbly, 5 to 7 minutes. Cover the pan and cook over low heat for 15 minutes.

Heat remaining oil in another pan over medium heat. Saute cabbage until tender, about 5 minutes. Add cinnamon and ginger. Stir mixture into ground beef mixture and continue to cook over low heat, covered, for 5 minutes, adding 1 tablespoon of water if mixture is dry.

Rinse and drain rice; transfer to a pot. Add cold water, butter, and remaining salt. Bring mixture to a boil, uncovered. Reduce heat to medium-low and simmer until rice is half-cooked and water has evaporated, 10 to 15 minutes. Fluff with a fork.

Add beef mixture to the rice and slowly mix to incorporate. Turn the heat to low. Add hot water and reserved 1/4 cup brewed saffron to the rice, cover the pot, and let cook until rice is tender, about 20 minutes.