Making Du'aa When Breaking Your Fast

Invocation should be made before iftaar (breaking the fast), at Maghrib, because this combines weakness and humility, and because he is still fasting. All of these are means of having one's invocation answered. After breaking the fast, one is relaxed and happy, and may become negligent.

But there is a Hadith from the Prophet (peace and blessings of Allah be upon him) which, if it is Sahih, shows that the invocation may be made after breaking the fast. It said: "Thirst has gone, the veins are moist, and the reward is assured, if Allah wills." (Narrated by Abu Dawud; classed as hasan by al-Albaani in Sahih Sunan Abi Dawud, 2066)

This can only mean after breaking the fast. Similarly it was narrated that some of the Companions said: "O Allah, for You I have fasted and with Your provision I have broken my fast."

So you may pray to Allah and say whatever invocation you think is suitable.