Preheat your oven to 200°C (390°F).
Peel the sweet potatoes and carrots, then cut them into even chunks about 2.5 cm (1 inch) in size.
Toss the vegetable chunks with a tablespoon of olive oil, salt, and pepper, ensuring they are well coated.
Spread the vegetables evenly on a parchment-lined baking sheet.
Roast in the oven for 25 to 30 minutes until the edges are caramelized and the vegetables are tender when pierced with a fork.
While roasting, chop the onion and sauté it in a large pot with a tablespoon of olive oil over medium heat for about 5 minutes until translucent and fragrant.
Add the minced ginger to the onions and cook for another minute, releasing a spicy, fragrant aroma.
Once the roasted vegetables are ready, add them to the pot with the sautéed onion and ginger.
Pour in the vegetable broth, enough to cover the vegetables, and bring the mixture to a gentle simmer.
Let the soup simmer for about 10 minutes to meld the flavors.
Use an immersion blender to puree the soup directly in the pot until smooth and velvety.
Taste the soup and adjust seasoning with salt, pepper, and a squeeze of lemon juice for brightness.
Serve the soup hot, garnished with fresh herbs or a drizzle of cream if desired. Enjoy the warm, earthy flavors!