Make quark yourself
Living in the US, where there is not even an English word for Quark, let alone the product itself, I finally found a way to always have fresh quark in the fridge!
Here is the recipe:
from 1 gallon 2% milk (about 4 liters) remove about one cup and replace with buttermilk.
Let the mixture stand for 3 days at elevated room temperature. I always use the oven here with the lights on, that's warm enough. After three days, the whey has separated from the cottage cheese, put the quark in a cloth and drain in the refrigerator, the remaining whey, which may take another day. Remains about 800g the best delicious Quark.