Preheat your oven to 200°C (390°F). Line a baking sheet with parchment paper to help with easy cleanup.
Trim the dark green tops and root ends from the leeks. Slice them in half lengthwise, then into 2-3 inch segments, keeping the pieces relatively uniform for even roasting.
Arrange the leek pieces cut side up on the prepared baking sheet, spacing them out to allow for caramelization.
Using a pastry brush or spoon, drizzle the olive oil generously over the leeks, making sure each piece is well coated. This helps them brown beautifully and develop their sweet flavor.
Sprinkle sea salt evenly over the leeks, and crack fresh black pepper on top. Add herbs if you like, placing sprigs among the leeks for fragrant notes.
Place the baking sheet in the oven and roast for about 25-30 minutes, until the leeks are tender and edges are golden and caramelized. Check halfway through and rotate the pan if some pieces are browning faster.
Once the leeks are beautifully browned and fragrant, remove from the oven and let them rest for 5 minutes. This allows the flavors to settle and the texture to become perfectly tender.
Squeeze a little lemon juice over the roasted leeks for a bright finishing touch if desired. Serve warm, drizzled with a bit more olive oil or topped with fresh herbs for extra flavor.
