Cook the rice according to the instructions and let it cool down.
Peel the potatoes, wash the zucchini and mushrooms and coarsely grate on a grater. Squeeze the potatoes and zucchini vigorously in a kitchen towel, otherwise the batter will be too runny and the rösti will become crumbly.
Mix the rice, vegetable mixture, eggs and flour in a bowl and season with pepper, salt and nutmeg to taste.
Let some olive oil get hot in a pan and bake the rösti in portions on both sides until crispy.
Meanwhile, stir the dip quickly. Mix the quark, milk, herbs and the chopped tomatoes and shallots together in a bowl and season with salt and pepper.