Wash the cucumber, dab dry and cut lengthwise into thin slices with a wide peeler. Clean the radishes, wash, drain and cut into sticks. Roast sunflower seeds in a pan without fat and remove.
Peel garlic and onion. Chop the onion finely, press the garlic through a garlic press. Wash the dill, dab dry and chop finely, except for a little for garnishing. Mix yoghurt, quark, lemon juice, garlic, onion and dill, except for a little bit for garnishing.
Season to taste with salt and pepper. Arrange cucumber and radishes on a large plate and pour the sauce over them. Drizzle with olive oil. Sprinkle with sunflower seeds and remaining dill. Serve garnished with dill flags, dill flowers and lemon wheels.
For example, lamb chops and pita bread taste good with it.