01 - Heat the olive oil or coconut oil in a large pot or Dutch oven over medium heat. Add the diced onion and cook, stirring occasionally, for 3–4 minutes until softened and translucent.
02 - Add the minced garlic and grated ginger to the pot. Cook for 1 minute more, stirring constantly, until fragrant.
03 - Stir in the red Thai curry paste. Cook for 1–2 minutes, stirring frequently, to release its aromatic oils and deepen its flavor.
04 - Add the cubed butternut squash to the pot and toss to coat thoroughly with the curry paste mixture.
05 - Pour in the vegetable broth and stir to combine. Bring the soup to a boil over medium-high heat, then reduce the heat to low, cover, and simmer gently for 20–25 minutes, or until the butternut squash is fork-tender.
06 - Stir in the coconut milk and soy sauce (or tamari). Continue to simmer uncovered for an additional 5 minutes to allow the flavors to meld.
07 - Remove the pot from the heat. Using an immersion blender, carefully puree the soup directly in the pot until smooth and creamy. Alternatively, transfer the soup in batches to a countertop blender and process until smooth, ensuring the lid is vented to release steam, then return to the pot.
08 - Taste the soup and adjust the seasoning with salt, freshly ground black pepper, and fresh lime juice as needed for your preference.
09 - Ladle the hot Thai curry butternut squash soup into individual bowls. Garnish generously with chopped fresh cilantro and sliced red chili, if desired.