Preheat your oven to 220°C (425°F). Line a baking sheet with parchment paper or a silicone mat for easy cleanup.
Wash and dry the radishes thoroughly, then trim off their tops and tails. Slice the radishes in halves or quarters depending on their size, aiming for uniform pieces.
Peel the carrots and cut them diagonally into approximately 1/2-inch thick slices. This shape helps them cook evenly and looks appealing when roasted.
In a large mixing bowl, toss the radishes and carrots with 2 tablespoons of olive oil, making sure each piece is well coated. This helps them develop a crispy exterior and rich flavor.
Sprinkle the vegetables generously with coarse sea salt and freshly cracked black pepper. Add the sprigs of thyme or rosemary if using, then toss again to distribute the seasonings evenly.
Spread the vegetables out in a single layer on your prepared baking sheet, ensuring they are not crowded. This promotes even roasting and caramelization.
Place the baking sheet in the oven and roast for about 20-25 minutes. Halfway through, use tongs or a spatula to toss the vegetables gently, so they brown evenly and develop those smoky, gooey edges on the radishes.
Look for the radishes to shrink slightly and turn a golden brown around the edges, with a gooey, caramelized appearance. The carrots should be tender and glossy, with brown bits indicating caramelization.
Remove the vegetables from the oven and transfer them to a serving dish. Drizzle with a tablespoon of balsamic vinegar if you like a tangy brightness, and toss gently to coat.
Let the vegetables rest for a few minutes, then taste and adjust seasoning if needed. Garnish with fresh herbs or a pinch of flaky sea salt for extra flavor. Serve warm and enjoy the smoky, sweet roasted vegetables!
