- 1 pound ripe but firm small round or plum tomatoes, cut into 1/2-inch-thick wedges
- 2 medium yellow onions, cut into 1/4-inch-thick wedges
- 1 tablespoon finely slivered orange zest (see Tip)
- 1 tablespoon extra-virgin olive oil
- 1 tablespoon chopped fresh thyme leaves, plus sprigs for garnish
- 1/2 teaspoon kosher salt, divided
- Freshly ground pepper to taste
- 1 pound boneless, skinless cod or other thick-cut, firm-fleshed fish, cut into 4 equal portions
- Preheat oven to 400 degrees F.
- Combine tomatoes, onions, orange zest, oil and chopped thyme in a 3-quart glass or ceramic baking dish. Sprinkle with 1/4 teaspoon salt and pepper; stir to combine.
- Roast, stirring occasionally, until the onions are golden and brown on the edges, about 45 minutes. Remove from the oven. Increase oven temperature to 450 degrees F.
- Push the vegetables aside, add fish and season with the remaining 1/4 teaspoon salt and pepper; spoon the vegetables over the fish.
- Return the baking dish to the oven and bake until the fish is opaque in the center, about 10 to 12 minutes. To serve, divide the fish and vegetables among 4 plates and garnish with thyme sprigs.