Dice the onion and garlic cloves and sauté in a pan with olive oil until translucent.
Do not peel the cucumber, cut in half and core with a teaspoon. Chop 1.5 cucumbers into large pieces and place in a kitchen blender with the onions and garlic. Add the sour cream, vegetable stock and two tablespoons of vinegar and puree everything. Season well with salt, sugar and pepper. Finely chop the dill and mix too. Cut or pin the remaining cucumber into thin slices and mix with the soup. Chill in the freezer for 20 minutes or in the refrigerator for an hour.
You can also try sour cream or yogurt instead of sour cream.
If necessary, add seasoning to the ice-cold soup and drizzle with a little olive oil for serving. Decorate with the remaining dill tips if you like.