In a large pot on medium-high heat, warm the coconut oil. Add onions and allow to cook for 4-5 minutes until translucent.
Add garlic and ginger, and cook for about 1 minute. Add curry powder, cumin, turmeric and salt, and allow to heat for an additional 30 seconds until fragrant.
Add lentils and chopped sweet potatoes to the pot and stir to combine with the spice mixture.
Cover with coconut milk and broth, stir to combine, and bring to a gentle boil. Once boiling, reduce to a simmer, cover, and allow to cook for about 15-20 minutes until lentils are tender and the sweet potatoes can easily be pierced with a fork.
Once tender, add chopped spinach, stir to combine, and simmer until spinach has wilted. At this point, the curry should have thickened and most of the broth absorbed, if not, allow it to simmer for a final 5-10 minutes until the curry is thick and creamy. If you find the curry too thick, simply loosen it up with a bit of additional broth or water. Once cooked, taste and adjust the seasoning with additional salt to taste.
Serve curry immediately or store in an airtight container in the fridge for up to 5 days or in the freezer for up to 3 months.