Heat the olive oil in a Dutch oven set over medium-high heat. Add the onions and cook for 2 minutes. Stir in the garlic and cook for 20 seconds. Stir in curry paste and ginger; continue to cook for 30 seconds or until fragrant.
Add the squash and generously season with salt and pepper. Stir in the coconut milk and vegetable broth; bring to a boil. Reduce heat to medium and continue to cook for 10 to 15 minutes or until the squash is very tender.
Stir in the lime juice and taste the soup for salt and pepper; adjust as needed.
Using an immersion blender, blend the soup until smooth. You can also blend it in a blender in batches. Taste for seasonings and adjust accordingly.
Ladle the soup into bowls.
Garnish with yogurt, cilantro, pumpkin seeds, and/or sriracha sauce, and serve.
Squash Substitute: You can use almost any winter squash in this recipe, from acorn to pattypan.
Coconut Milk: Use full-fat coconut milk for a thicker, more decadent soup.
Balancing Sweetness: Butternut squash can vary in sweetness. If your soup turns out too sweet, balance it by adding more lime juice or a touch of apple cider vinegar to cut through the sweetness.
Texture Adjustment: Adjust the texture of your soup by adding more liquid (vegetable broth or water) if it's too thick or simmer it longer to reduce it if it's too thin.
Spice Control: Be cautious when adding spicy ingredients like curry paste if you're not accustomed to heat. You can always start with a smaller amount and gradually add more to taste.
Roast The Squash: Roasting the butternut squash before adding it to the soup can intensify its flavor. Drizzle the squash cubes with olive oil, season with salt and pepper, and roast in the oven for 20 to 25 minutes or until it's soft and slightly caramelized.