Peel the onion and cut into small cubes. Wash and drain the lentils. Bring the onion, lentils and approx. 300 ml water to the boil and simmer at low heat for 10-15 minutes (the liquid should be completely boiled, otherwise drain).
Wash the cucumber and slice into thin slices. Mix cucumber and vinegar and season to taste with salt, pepper and a little sugar. Let the lentils cool down. Add egg yolk and flour, season with salt, pepper and ginger and form 2 roastings of the same size.
Heat the oil in a frying pan and fry the roasts for 3-4 minutes on each side until golden brown. Wash the coriander, dab dry and chop finely, except for one leaf. Mix yoghurt, chopped coriander and lemon peel and season with salt, pepper and 1 pinch of sugar.
Serve roasts with yoghurt sauce and cucumber salad and garnish with pink pepper berries.