If you are planning to visit Vietnam but don't know where to go for halal food then please check out these places:  (We are in the process of compiling this list, please have patience with us)
 

South Vietnam

You need a local Muslim to take you to these places (just ask the Imam from the Dong Du Mosque for assistance):

66 Dong Du, District 1: Indian, Vietnamese cuisine.  This mosque has a halal food court where you can buy lunch or dinner. Many Muslim foreigners come here to eat.
26 Bui vien, District 1: Indian, Pakistani.
45 Nam Ky Khoi Nghia: Malay, Indo cuisine.
459B Tran Hung Dao: Pho (noodle).
94/4A Huynh Van Banh (near fashion shop of Ms.Basiroh): Budget food.
52 Nguyen Van Troi: Goat Cari (cari de).

An Giang 

Café Vila, 25 Nguyen Huu Canh, Chau Doc town.

                            phone: 867129; Indian food

53 Ba Trieu, Hanoi.
10 Hang Thung, Hanoi.
Nisa Restaurant: 90 Nguyen Huu Huan:  Malay and Indian cuisine.  Email: nisarestaurant@hn.vnn.vn

(N.B. you can get halal food in hotels but you need to pay more for them)