Peel and cut kumara into thick slices, add to the pan and turn heat down to a steady simmer. Put the timer on for six minutes.
While the kumara is cooking, mix your dressing ingredients in a small jar. Seal it and shake until smooth and well combined.
When the timer goes off (the kumara should be just cooked), add the chopped spinach to the pan for 30 seconds to a minute, then drain everything in a colander.
Assemble kumara, spinach and black beans in a bowl. Sprinkle pumpkin seeds over the top, pour over the dressing and devour.
If you're making this for a packed lunch, keep the dressing on the side in a little jar until you're ready to eat.