Preheat the oven to 450 degrees F. Line a baking sheet with parchment paper.
On the prepared pan, toss the green beans, radishes and white scallions with 2 tablespoons olive oil and ½ teaspoon salt. Arrange in an even layer and roast in the oven for 10 minutes, or until the vegetables are starting to shrivel.
Meanwhile, make the sauce: in a small mixing bowl or 2-cup measure, whisk together the miso, red curry paste, lime juice and 2 tablespoons olive oil.
Remove the pan from the oven and toss the veggies with the green scallions and half of the red curry mixture until well-coated. Return to an even layer and nestle the cod loins in the veggies so they are touching the bottom of the pan. Season the fish with salt and slather with the remaining marinade so it’s fully coated in every nook and cranny.
Return to the oven for 10 minutes, or until the fish is cooked through and the vegetables are caramelized and tender. Serve immediately over white rice or more veggies.