For a business lunch and casual lunch with friends, here is a list of 3 places where set-lunches are under 180,000 VND in district 3.
La Belgique is a French restaurant located on 17 Tran Quoc Toan. The set-lunch is at 160,000 VND including 2 courses, a choice between two starters and main courses. The starters are either a salad (Mediterranean, mix or salad with bacon and poached eggs) or a soup (oyster mushroom, gazpacho, asparagus or potatoes soup). For the main course, they usually propose a poultry dish and another dish with pasta or meat. Beside the set menu, La Belgique also serves typical dish from Belgium such as mussels, and Mediterranean food such as couscous.
Twenty21One is a nice restaurant on 21 Ngo Thoi Nhiem, where you can have lunch by the pool. The restaurant offers a menu at 180,000 VND including a soup of the day, mixed or Cesar salad, a main course between 21 mediterranean, western and asian, different dishes such as chicken shish taouk, croque monsieur or Thai red curry of duck, a dessert of the day and a soft drink or iced tea. See the full menu here.
Shri Restaurant & Lounge on Level 23 of the Centec Tower, 72-74 Nguyen Thi Minh Khai, offers a set-lunch menu at 180,000 VND ++. The food has Asian and panish influence with classic Mediterranean dishes, international favorites and Asian flavors. The menu includes Shri iced-tea, daily soup, vegetables, salad, potatoes with fried egg, daily dessert with a choice of 8 different main courses. See the lunch menu here.