gluten free, dairy free, vegetarian - how did it do this?

To determine this, The OpenSauce cleverly checks the food groups of all the ingredients in the recipe. Therefore Gluten free, diary free and vegetarian special diets are automatically determined by the ingredients in the recipe.

If however the food group of an an ingredient has been incorrectly defined, then incorrect diet information may be reported. This can be easily fixed by anyone: Simply sign-in (if not already), click on the ingredient link in the recipe preview, click edit, and select the correct food group for that ingredient. Voilà!