Set your oven to 400F or 200C. Prick the sweet potatoes all around with a fork about an inch apart. Line a baking sheet with parchment and brush the sweet potatoes lightly with oil. Roast them for 40 to 60 minutes until a fork slides in easily.
In a mixing bowl, combine black beans, chopped tomatoes, corn, cilantro, red onion, and diced garlic. Pour over lime juice and olive oil, then season with sea salt, pepper, and chili flakes. Stir everything together well.
Make the guacamole by mashing the avocado with lime juice and a pinch of sea salt until smooth.
Whisk the coconut yogurt with lime juice and sea salt in a separate bowl to create the vegan sour cream.
Once the sweet potatoes are done, slice them in half lengthwise. Spoon the black bean mixture into each half, top with the guacamole, and finish by drizzling the vegan sour cream over the top.