Question Summary:
I fasted on Aashoora’, but forgot during a moment of lunchtime rush – and ate a sandwich. Besides the lapse in memory, I had made my fasting intention and fasted all that day.

Question Detail:

I fasted on Aashoora', but forgot during a moment of lunchtime rush - and ate a sandwich. Besides the lapse in memory, I had made my fasting intention and fasted all that day.

Was my fast accepted?

Answer :

In the name of Allah, Most Gracious, Most Merciful
Assalaamu `alaykum waRahmatullahi Wabarakatoh
The fast was valid. 
And Allah knows best
Wassalam
Mufti Ebrahim Desai
Darul Iftaa, Madrassah In'aamiyyah