There are many substitutions to replace beef for a vegetarian or vegan Wellington. Of course, in this recipe we use a mushroom lentil filling, but you can try out other ingredients too. Chickpeas, red beans, green peas, yellow peas, red lentils, nuts, and seeds can all deliver a meaty texture. You can even use vegan ground beef for a quick and easy alternative, although this option tends to be less healthy.