Peel and halve the shallots. Peel and wash the cucumber, cut into quarters lengthwise and remove seeds. Dice cucumber. Cut sausage into slices. Fry in hot oil while turning for about 3 minutes and remove. Fry the shallots and cucumber cubes in the cooking fat for about 10 minutes.
Season with salt and cayenne pepper. Deglaze with 1/2 litre water and let it boil for another 10 minutes. In the meantime wash and chop the herbs. Stir sour cream and cornstarch until smooth and add to the pan. Add slices of sausage and herbs, bring to the boil again briefly and season to taste with salt, pepper, mustard and lemon juice. Serve everything garnished with fresh herbs and lemon slices