Preheat oven to 200°C.

Chop the beetroots, carrots, and sweet potatoes into roughly equal-sized pieces.

Toss the chopped vegetables with olive oil, salt, and pepper on a baking sheet.

Roast for 30-40 minutes, or until tender and slightly caramelized.

While the vegetables are roasting, sauté the onion and garlic in a pot until softened.

Add the roasted vegetables to the pot and pour in the vegetable broth.

Bring to a boil, then reduce heat and simmer for 10 minutes.

Use an immersion blender (or transfer to a regular blender) to blend the soup until smooth and creamy.

Season with salt and pepper to taste.