1. In a bowl, put the flour, 3/4 cup water, garlic, parsley, mustard and 2 tablespoons salt.
2. Whisk very well until completely integrated. Set aside.
3. Clean the mushrooms very well.
4. Pour the breadcrumbs onto a plate.
5. Dip each mushroom into the mixture and then dip them in the breadcrumbs.
6. Put the battered mushrooms on a plate, add oil on top, and bake for 10 minutes at 350ºF.
7. Check the doneness, making sure they are golden brown.