First, peel cucumbers and cut in half lengthwise. Scrape out the seeds with a spoon and cut the flesh into coarse cubes.
Finely puree cucumbers with buttermilk, garlic cloves and onion in a tall container with a hand blender.
Season with salt, pepper and olive oil to taste. Refrigerate for at least 1 hour.
Stir well before filling or blend again briefly and serve sprinkled with sesame seeds.
Preparation Tip:
The cold dish also tastes good garnished with basil or mint.