I make this and several other Iranian dishes and was taught by my mother in law, who makes the best rice (I go to Iran regularly so I have had a lot of persian rice). There are a few tricks I saw in various reviews so let me put it together. The key to perfect rice and perfect tadik is to a few things. First make sure you boil your rice with a lot of salt. we use approx 1/3 cup. You will rinse most of it off when you drain the rice prior to putting it back in the pot so you can get it to your preference. Secondly, when you are boiling your rice, wait til it rises to the top and look for stripes in the rice. If you put it on your spoon you can actually see the stripes in the rice which lets you know it is ready.
Once you have added your sabzi,before you place your rice back into the pot for steaming, poor about 1/4 cup oil in the bottom of the pot, poor your rice in the pot and put it a mound making a hole in the middle so that it looks like a volcano. Add about another 1/4-1/3 cup of oil and poor it all over the rice. Take 2 paper towls and place it over the top of the pot and then put your lid on. steam on high for about 10 min, then med for 10 min, then low for 10 min. This will produce the perfect tadik and rice as a whole