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.
Notes
Feel free to use frozen broad beans if you cannot obtain fresh ones.
Broad beans are also known as fava beans
If you cannot obtain broad beans then use cooked/canned lima/butter beans instead.
Be sure to thoroughly mix the tapioca starch and water together while pouring the liquid into the pan.
You can use a non skin skillet/dutch oven/casserole dish to make this recipe.
If you don't have whole mustard and cumin seeds use dried and simply add the spices along with the others.