Start by adding the olive oil to a non stick frying pan and preheat on low. Allow the cumin and mustard seeds to heat through until they begin to crackle.
At this point we can add the onions and garlic, increase the heat to medium, sautéing the ingredients until transculent.
Now is a good time to add the remaining spices - again saute everything for a further 3-4 minutes - by now a lovely aroma should permeate the air.
Add the tamarind, broad beans, tomatoes, sweet potatoes and tapioca starch infused water.
Reduce the heat to low, cover pan/pot and leave to simmer for 20-25 minutes.
Half way through simmering time the sauce will being to thicken. If the water recedes replenish with ¼ cup of water.
Do a taste test and adjust seasoning if required and serve accordingly.
