River Cottage Veg
This is one of the most approachable vegetarian cookbooks I have ever read. I have cooked about 20 of the dishes and everyone turned out as expected. The ingredient lists for each recipe are fairly short and most everything is possible to find in a reasonably stocked grocery store. The author shows, through the sheer approachability of his recipes, that he wants readers to be able to eat a more plant based diet. All recipes are vegetarian and many are vegan or can be made so. This is my favorite vegetable cookbook. The other books in the River Cottage series are also worth looking into.