Peel and cube pieces of purple yam, white yam and cocoyam. Bring cocoyam to a boil and cook until just tender. Steam purple* and white yams. Allow to cool. Combine yams and cooked Madagascar beans in a bowl.
Make a dressing by combining coconut yoghurt, lemon juice and tamari in a screw top jar. Add in finely chopped parsley, chives and chervil, shake well to combine. Pour enough dressing over vegies and beans to lightly coat. Serve chilled.