Preheat your oven to 400°F (200°C), then spread the cubed sweet potatoes on a baking sheet. Drizzle them with olive oil, toss to coat evenly, and roast for about 25–30 minutes until they’re tender and slightly caramelized.
While the sweet potatoes roast, heat a tablespoon of olive oil in a large pot over medium heat. Add the chopped onion and sauté for 5–7 minutes until it becomes translucent and fragrant, stirring occasionally.
Add the minced garlic to the onions and cook for another minute; the mixture will smell fragrant and the garlic will turn slightly golden.
Pour in the vegetable broth, then bring it to a gentle simmer. Add the roasted sweet potatoes (they should be soft and flavorful) and the drained black beans.
Let the soup simmer for about 10 minutes to allow flavors to meld and the beans to heat through. Season with salt and pepper to taste.
Use an immersion blender to blend the soup directly in the pot until smooth and velvety, or carefully transfer it in batches to a blender and puree until creamy.
Return the blended soup to a gentle simmer for a few more minutes, adjusting seasoning if needed.
Serve the soup hot, garnished with a drizzle of olive oil or fresh herbs if desired, alongside crusty bread or a simple salad.
