The tartar sauce should consist of 1/4 soy milk and 3/4 oil, I usually make 75 ml soy milk with 225 ml oil. It helps if both liquids are at the same temperature, but it`s not absolutely necessary - I find the consistency a little better then.
Put all liquids and a little salt in a tall container and puree with a blender. Chop the herbs and stir in.
Finished! Tastes good e.g., on a wholegrain sandwich with tomatoes, lettuce, vegan cheese and pickles. But also perfect with french fries and country potatoes.