Heat oil in Dutch oven or a large saucepan over medium heat. Add carrots, onion, garlic, & ginger. Sauté until onion is translucent, about 10 minutes. Add broth, cover, & simmer, stirring, occasionally until carrots are tender, about 30 minutes.
Once carrots are tender, puree soup with an immersion blender or in batches in a blender. In a small bowl, whisk together the miso & half a cup of the soup. Stir the mixture back into the pot of soup. Season with salt, pepper, or additional miso to taste.
Ladle into bowls and garnish with a drizzle of sesame oil and pickled scallions