Preheat your oven to 200°C (400°F). Line a baking sheet with parchment paper to keep things tidy and ensure even roasting.
Trim off the woody ends of the asparagus, about 1 inch from the bottom, then spread them out evenly on your prepared baking sheet.
Drizzle the asparagus generously with olive oil, then use your hands or tongs to toss them until evenly coated. Sprinkle with flaky sea salt and freshly cracked black pepper for flavor.
If using garlic, scatter the thinly sliced cloves over the spears for added aroma and flavor. Toss gently again to distribute evenly.
Place the baking sheet in the oven and roast for 12 to 15 minutes. You'll see the tips caramelize slightly and the asparagus become tender with a smoky edge.
While the asparagus roasts, pour the balsamic vinegar into a small skillet and bring to a gentle simmer over medium heat. Reduce the vinegar, stirring occasionally, until it thickens into a glossy, syrupy glaze that coats the back of a spoon, about 8-10 minutes.
Once the asparagus is done, transfer it to a serving platter. Drizzle generously with the balsamic glaze, letting it pool slightly around the spears for a beautiful presentation.
If desired, use a microplane to zest a little lemon over the top for a fresh, bright finish that balances the richness of the glaze.
Serve immediately while warm, enjoying the combination of tender, smoky asparagus coated in sweet balsamic and brightened with lemon zest.