Sweet potatoes - you will see them in my dishes a lot. 
Sweet potatoes, compared to normal potatoes, have low glycemic index.
Sweet potatoes are a great source of beta-carotene, a powerful antioxidant, which is converted to vitamin A in the body. Consuming foods rich in beta-carotene may reduce the risk of developing certain types of cancer, offer protection against asthma and heart disease, and delay aging and body degeneration.
One medium-sized potato contain more than 100 % of the recommended daily amount of vitamin A and more than two thirds of the recommended daily allowance of vitamin C. 
Keep the skin on! The colour of sweet potato skin can vary from white to yellow, purple or brown but no matter what color it is, make sure you do not peel it off. Sweet potato skin contributes significant amounts of fibre and potassium.
Many studies suggest that sweet potatoes decrease the risk of obesity, diabetes, heart disease and also promote healthy complexion, increased energy, and overall lower weight.