Meatballs with delicious kohlrabi and carrot vegetables

Ingredients for 4 servings
1 piece of wheat bread roll
1 piece of onion/s
400 g tartare, raw
2 tbsp low-fat quark
1 teaspoon mustard, classic
1 piece of chicken egg/s
1 pinch(s) of iodized salt
1 pinch(s) of pepper
3 tsp parsley
4 bulb(s) of kohlrabi
6 pieces of carrots/carrots
1 serving(s) of Weight Watchers Meeting Products Hollandaise Sauce
400 ml water
2 tsp vegetable oil