Pour the mushroom sauce over the green beans and give it a gentle stir to coat. Top with the fried onions. Cover the baking dish with foil and bake for 20 minutes. Remove the foil and bake for another 10 minutes, or until the onions turn a deep golden brown and the sauce is bubbling. Allow the casserole to cool for 15 minutes before serving.
https://cooking.nytimes.com/recipes/1021624-vegan-green-bean-casserole