Preheat your oven to 200°C (390°F) and line a baking sheet with parchment paper for easy cleanup.
Wash the radishes thoroughly, then trim off the stems and any root ends. Slice them in half lengthwise to promote even roasting.
Peel the garlic cloves and give them a light crush with the side of a knife or mince finely. Set aside.
In a mixing bowl, toss the radish halves with the olive oil to coat evenly. Sprinkle with salt and freshly cracked black pepper.
Spread the radishes cut-side down on the prepared baking sheet, arranging them in a single layer. Distribute the garlic cloves among the radishes.
Place the tray in the oven and roast for about 20-25 minutes, until the radishes are golden and caramelized around the edges, and the garlic is fragrant and soft.
Halfway through roasting, use tongs or a spatula to flip the radishes for even browning, if needed.
Remove the tray from the oven once the radishes are tender and deeply caramelized, and the garlic is soft and slightly browned.
Transfer the roasted radishes to a serving dish, sprinkle with fresh herbs if using, and squeeze lemon juice over for a bright finish.
Let the radishes rest for 3-5 minutes to allow flavors to meld. Serve warm as a cozy, smoky side dish with a rustic charm.