1 Rinse and dry the cucumber, halve lengthwise and scoop out seeds with a spoon. Finely grate the cucumber on a box grater.
2 Place the quark in a clean kitchen towel and squeeze well to extract excess liquid.
3 Put the drained quark in a bowl. Squeeze juice from the lemon and add juice and cucumber to the quark. Season with salt and pepper and stir to combine.
4 Rinse the spinach in several changes of cold water, then spin dry well.
5 Peel the shallot and very finely dice. Split the baguette rolls and spread quark mixture on bottom halves.
6 Layer bottom roll halves with spinach and smoked turkey and sprinkle with the chopped shallots. Sandwich with top roll halves and serve.