For the dressing:
3 Tbsp extra virgin olive oil
1/2 tsp agave nectar or honey, or to taste
2 Tbsp roughly chopped fresh basil
1 tsp roughtly chopped fresh mint
Pinch each of kosher salt and fresh black pepper
For the salad:
1 large seedless (English) cucumber
Preheat oven to 400°F. Line a small rimmed baking sheet with foil. Cut the lemon into quarters, and place cut side up in the baking dish. Roast for 12-14 minutes, until the edges of the lemon wedges are lightly browned. Remove from the oven and set aside to cool for a couple of minutes.
Using a mandoline, or a very sharp knife, slice the cucumber into 1/8-inch-thick slices. Arrange the slices on a platter.
Into a small food processor or blender, squeeze the juice from the roasted lemon quarters. Add the remaining ingredients for the dressing, adjusting with more agave or honey, salt, and pepper to taste.
Pour the dressing over the cucumber. Let the salad sit at room temperature for 15 minutes before serving. Don't let it sit longer, or the salt in the dressing will begin to draw the liquid out of the cucumber, and you'll have a watery salad.