Some old vegetarian soup recipes contain milk & butter. Why? Soy milk replaces dairy but what about butter?

Question

I appreciate that most vegetarians use dairy milk products, including butter, but that some don't. And Vegans will not touch any animal or animal derivate. That been the case what would you substitute butter for in a soup recipe. I'm assuming the butter is to give a bit more body.

Answer 1

You could use margarine. If it's a very old recipe, margarine may not have been invented yet.

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Answer 2

I use a vegan "butter".  It says vegan right on the label.