a handful of basil leaves (about 2 dozen),washed and dried
Preheat the oven to 250°F.
Coat a large oven safe pot, fitted with a lid (a Dutch oven is perfect) with the grapeseed oil. Warm the oil over medium-high heat. Then add the curry leaves and let them sizzle for about 30 seconds. Use a slotted spoon to remove the leaves, making sure to let all of the excess oil drain off the spoon and back into the pot. (The leaves can be discarded.)
Reduce the heat to medium-low and add the onion to the pot. Cook until it's soft, about 5 minutes. Then add the ginger, garlic and spices. Cook until this becomes very aromatic, about 3 minutes.
Add the sweet potato, lentils and corn to the pot. Stir to combine.
Mix the coconut milk with the vegetable broth and then add it to the pot. It should just about cover the vegetables. Cover the pot and place it in the preheated oven for about 3 hours. When it's done, the lentils should be tender and the potatoes should look almost pureed. Gently stir the stew about every 45 minutes or so.
Remove from the oven, add the basil leaves, and season to taste with sea salt if necessary.