1 Coarsely grind mustard seeds in a mortar or crush with the side of a large, heavy knife.
2 Pat beet dry with paper towels and cut into long strips (about 5 mm or 1/4 inch wide).
3 In a bowl, mix together mustard seeds, a pinch of salt and a little pepper.
4 Rinse herbs and shake dry. Pluck parsley leaves and chop finely. Thinly slice chives.
5 Mix together both herbs with the mineral water and quark in a small bowl. Season with salt and pepper and serve with the beet salad.