Kenya has spent 25 years developing a purple "supertea" with high levels of antioxidants. The hope is that the tea will appeal to health-minded consumers and revive the country's struggling industry.

Wash the beans thoroughly. Slice them on the diagonal into 3-4cm pieces and set them aside. Put a steamer or large pan of water (to cook the beans) on high heat and bring the water to the boil.

Wash the beans thoroughly. Slice them on the diagonal into 3-4cm pieces and set them aside. Put a steamer or large pan of water (to cook the beans) on high heat and bring the water to the boil.

If you use one cup of Simple Green, you will need to add 30 cups of water to make a 1:30 dilution (or ½ a cup Simple Green to 15 cups water. Advertisement. Article continues below this ad ...