Heat a large pot over medium heat and add the onion, garlic, and ginger. Cook until the onion softens.
Stir in the Thai red curry paste and cook for one minute until fragrant.
Add the butternut squash cubes and sliced carrots. Pour in the vegetable broth and bring to a boil.
Reduce heat, cover, and simmer for 20 minutes until the squash and carrots are tender.
Remove from heat. Use an immersion blender to puree the soup until smooth.
Return the pot to low heat. Stir in the coconut milk, lime juice, and salt. Heat through without boiling.
Ladle into bowls and top with fresh cilantro.