Preheat oven to 400F.
Place cut sweet potatoes and squash on a large baking sheet, toss with 1 tablespoon of olive oil and roast for 30 minutes.
In a large pot, drizzle with 1 tablespoon of olive oil over medium heat. Add onions and cook until fragrant, about 2-3 minutes. Add garlic, ginger, curry, salt and red pepper flakes, and cook for another 2-3 minutes.
Add roasted vegetables and cover with broth or water.
Bring to a boil, reduce heat to low, cover and simmer for 15-20 minutes.
Turn off heat, add in coconut milk and lemon juice.
Blend the soup until silky smooth with an immersion blender or by working in batches with a regular blender.
Divide soup between bowls, serve.