Warm the olive oil in a large pot over medium heat, then add the onion, sea salt, and a few grinds of black pepper and cook for 5 to 8 minutes before stirring in the sweet potatoes and apple for another 8 to 10 minutes. The onion should turn soft and translucent, and the sweet potatoes should start losing their raw, firm look around the edges.

Mix in the garlic, ginger, coriander, and smoked paprika, then add the apple cider vinegar, 3 cups of the vegetable broth, and the coconut milk and bring the pot to a boil before covering and lowering to a simmer for 20 to 30 minutes. Once the spices hit the hot mixture, the pot should smell warm and fragrant, and the sweet potatoes are ready when a fork slides through with no resistance.

Let the soup cool slightly, then blend until smooth using a countertop blender in batches if needed, adding up to 1 more cup of broth if it feels too thick, and season to taste before serving with the reserved coconut milk and any desired garnishes. Before blending, the soup will look chunky and loose, and after blending it should look glossy, creamy, and fully unified with no visible bits.