Carrot-Lemongrass Soup

Ingredients:
- 1 tablespoon olive oil
- 1 tablespoon unsalted butter
- 1 cup onion, chopped
- 1 tablespoon kosher salt
- 2 lbs carrots
- 2 tablespoons lemongrass
- 1 tablespoon ginger
- 1 (14 ounce) can coconut milk
- 4 cups vegetable broth

Directions:
- "Heat a large soup pot over medium heat. When hot, add the butter and oil. When the butter has melted, add the onion, season with salt, and cook for five minutes, stirring occasionally, until the onion begins to soften. Add the carrots, lemongrass, and ginger, stir, and cover. Cook for ten minutes. Add the coconut milk and broth, bring the soup to a simmer, and simmer over low heat until the carrots are cooked through, about 20 to 25 minutes. Carefully puree the soup in a food processor or blender (or using an immersion blender). Return the soup to the pot, season to taste with salt, and serve hot.".