Vegetables and Herbs to Grow in a HDB

I read an article in the Straits Times on 18 July 2015 about growing your own edible garden in a limited space. 

It recommended six easy-to-grow vegetables and herbs. 

1. Sweet Potato Plant. Contains vitamins B and C. Leaves can be stir-fried. 
2. South African Leaf. Contains antioxidants, vitamins and iron. Can be boiled with green apples as detox beverage. 
3. Black Face General Leaf. Contains antioxidants and phenolic compounds. Simmer with citrus fruits as detox drink.
4. Roselle. Contains ascorbic acid, calcium and phosphorous. Great for tea recipes.
5. Prunella. Contains vitamins A, C and K. Great for salads and tea. 
6. Chinese Knotweed. Contains antioxidants. Great for salads and stir-fry dishes. 

I will be hunting down these seeds or seedlings and start growing them in my HDB balcony.