Wash and clean the cucumbers and radishes and cut or slice them into thin slices. Wash parsley, shake dry and cut the leaves of 3 stems into strips. Mix yoghurt, vinegar and wasabi and season to taste with salt, pepper and a little sugar.
Add oil. Mix yoghurt dressing, parsley strips, cucumber and radishes. Put the chickpeas on a sieve, rinse and drain. Peel onion and garlic and chop finely.
Coarsely chop 5 stems of parsley. Puree chickpeas, onion, garlic, parsley and egg yolk. Mix in breadcrumbs and flour and season to taste with salt, pepper, cumin and chili flakes.
Form about 20 balls with moistened hands. Fry in hot frying fat in portions for 4-5 minutes until golden brown. Drain on kitchen paper. Pluck parsley leaves from the remaining stems.
Season the cucumber salad with salt and pepper again and serve with the falafel. Garnish with parsley leaves.