Heat the butter in a wide sauté pan over medium heat until melted and frothy. Add the shallot, sliced fennel bulb, sliced fennel stalks, and celery and cook for 4-5 minutes or until just beginning to soften.
Prepare the Soup:
Add the vegetable stock and beans and bring to a boil. Reduce heat and simmer for 20 minutes. Taste and season with salt and pepper.
Finish the Soup:
Add the sugar snap peas, parsley, and dill. Nestle the trout fillets into the broth, cover, and cook for 5-7 minutes or until bright green and the trout is cooked through and opaque. Turn off the heat and stir in the lemon juice.
To Serve:
Ladle the soup into bowls and garnish with sliced watermelon radish and microgreens, if desired. Place a trout fillet on top and serve with a drizzle of extra virgin olive oil, if desired. Enjoy!