With the rack in the middle position, preheat the oven to 425°F (220°C). Line a baking sheet with parchment paper.
In a large pot over medium heat, soften the onions in the butter until translucent. Add the remaining vegetables and continue cooking for 2 minutes. Add the broth and milk. Bring to a boil and simmer, covered, for 30 minutes or until the vegetables are tender. Season with salt and pepper.
In a blender, purée the soup until very smooth. Add the sesame oil. Adjust the seasoning and keep warm.
Meanwhile, place the fish on the prepared baking sheet and drizzle with the oil. Season with salt and pepper.
Roast for 8 minutes or until flaky. With a fork, break up the fish into large chunks.
In a small bowl, combine the radishes, chives and lemon juice.
Divide the fish pieces among six shallow bowls. Pour the hot soup over the fish. Garnish with the radish mixture and drizzle with sesame oil, if desired.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.