RED - distinctive red skin, a creamy white firm textured flesh. Slice with skin on and bake with red onions.
ORANGE (Beauregard) - rich orange flesh and is the sweetest of the 3 varieties. Try in a caramelised roast vege salad.
GOLDEN - golden skin and flesh and a sweeter taste than red kumara. Try in a creamy chicken curry.
PURPLE - purple skin and flesh. Not as sweet as other varieties and they go well in a roast kumara salad.
Maori have grown kumara extensively since bringing it to New Zealand over 1000 years ago. They showed great skill cultivating and storing kumara, and managed to control the potentially devastating kumara caterpillar by using tamed black-backed seagulls. The original kumara were very small but in the early 1850s, a larger American variety was quickly adopted for its superior size and flavour. The majority of kumara are grown in Northland where the soil and climate are ideal. In other countries, kumara is known as sweet potato.
Kumara will retain their flavour and freshness for a week or two after purchase if you keep them in a cool, dark, well ventilated place. Don't store them in the fridge and keep them out of warmer temperatures to avoid sprouting. As with potatoes, if you peel the skin and throw it away, you're throwing away some of the goodness (fibre, vitamins and minerals), so just give kumara a good scrub and trim any bruising or woody bits. Kumara can be used as an alternative in any recipe that uses potatoes. You'll find they generally cook a little quicker than potatoes.
More sweet potatoe(kumara) recipe ideas here: http://allrecipes.com/recipes/1094/fruits-and-vegetables/vegetables/sweet-potato/