Chop the sweet potatoes into cubes (about 2 bites large) and chop the spinach roughly and set both aside.
In a medium sauce pan over a medium heat warm the olive oil and add the onions. Sweat the onions for about 1 minute before adding in the ginger and garlic. Once they’ve been added, continue to sweat the onions, ginger and garlic until everything is soft and very fragrant.
Add the Thai red curry paste to the pan and stir well to get everything coated. Add the sweet potatoes to the pan and stir once more. Pour the coconut milk and the water or stock into the pot so that the potatoes are just covered. Bring to a boil, then turn down to a simmer and continue to simmer until the potatoes are tender.
Once the potatoes are tender, remove the pan from the heat and add in the chopped spinach. Stir the spinach into the curry to wilt it. The residual heat will take care of this.
While the spinach is wilting, chop the cashews, basil and coriander until it resembles a fine crumb. You can either do this by hand or in a food processor.
Serve everything over a bed of steaming rice.