Tahchin can easily be reheated in the microwave. Add a damp paper towel over your rice and the steam will help puff up the rice and rehydrate it. The crispy tahdig is best the day you first bake your tahchin. Once reheated, it does soften. You can also reheat tahchin in a pot. This works best if you have a lot of tahchin to reheat. Add some oil to the bottom of the pot and place the tahchin crust side down and sprinkle a little over the rice. Heat over medium for 20 minutes, raising the temperature to medium high for 5 minutes to crisp up the crust.