Preheat the oven to 400 degrees F (200 degrees C).

Place carrots and cauliflower in a casserole dish; toss with garlic, olive oil, salt, and black pepper.

Roast in the preheated oven for 20 minutes. Stir and continue roasting until vegetables are tender and slightly charred, 25 more minutes. Remove from the oven and stir.

Bring vegetable broth to a boil in a large pot. Stir in curry powder and add roasted vegetables. Cover and boil soup until vegetables are soft, 8 to 10 minutes. Remove from heat.

Blend soup with a potato masher or an immersion blender until smooth. Return the pot to medium heat. Stir in coconut milk and lime juice; simmer until heated through, 5 to 10 minutes.