This is a fast and easy main dish that is flavorful yet feels light. You can use any seasoning blend you like though Mediterranean flavors work well with the roasted radishes. You can replace the radish here with diced rutabaga though it will increase the carbs a bit.
Preheat the oven to 425ºF and oil a rimmed baking sheet with avocado oil. Toss the radishes with herbs de Provence, avocado oil, salt and pepper. Roast for 10 minutes, until beginning to brown.
Combine butter, herbs, salt, and pepper. Spread onto fish. Remove the baking tray with the radishes and move the radishes around so that you can place the fish onto the tray. Roast together at 375ºF for another 10-15 minutes, or until fish flakes when tested with a fork.