Heat the oven: Set a rack in the center of the oven and heat the oven to 425°F.

Line a large rimmed sheet pan with parchment paper, or lightly oil the pan.

Start the vegetables: Put the carrots, fennel, and red onion on the sheet pan. Leave the radishes off the pan for now so they keep some shape and do not get too soft.

Drizzle 1 tablespoon of the olive oil over the vegetables.

Sprinkle the vegetables with 3/4 teaspoon of the salt and 1/4 teaspoon of the black pepper.

Toss the vegetables right on the pan until they are coated, then spread them into a single layer so the hot air can brown them.

Roast the vegetables for 10 minutes to give them a head start.

Mix the glaze: While the vegetables roast, whisk the orange zest, orange juice, Dijon mustard, honey, smoked paprika, the remaining 2 tablespoons olive oil, the remaining 3/4 teaspoon salt, and the remaining 1/4 teaspoon black pepper in a large bowl until smooth.

Put the halved radishes in a medium bowl. Spoon 1 tablespoon of the glaze over them and toss to coat.

Put the chicken thighs in the large bowl with the remaining glaze. Turn them until they are coated on all sides, then leave them skin-side up in the bowl so the glaze stays mostly on the meat and not on your counter.

Build the pan: Take the sheet pan out of the oven. Use a spatula to stir the hot carrots, fennel, and onion so they do not stick.

Add the radishes to the pan and spread them among the other vegetables.