If you are yearning for some burgers you might want to try the new "Bulls Burger" on the P9.
They have small assortment of Burgers, Hot-dogs and other fast-food and the quality is quite tasty (what I have tried so far).
It is a very small place and they only have a couple of tables outside, so it is rather for take away.
The place is located on the P9 coming from Tunis between the mosque Ain Zaghouan and the Carrefour/Soukra exit.
3 out of 5 times I stopped there, they could not serve (due to whatever reasons) so it was during regular opening hours.
So, stop by and they serve you inchallah...