In Saigon, having a good steak it is quite expensive. You have El Gaucho of course, but here are 3 other options to get a good beef steak without spending too much money!
B3 on 90 Nguyen Hue (1st floor)
They serve meat, burger, salad and plenty of craft beers. It is a good value for money, around 300k the steak + sauce + side dish (gratin dauphinois is very good). The venue has a small terrasse with view on Nguyen Hue, the staff pays a lot of attention to details, the steaks are always perfectly cooked. This is perfect for a dinner with good friends, a good beef and good beers.