Saute your diced onion in 1 or 2 tablespoons of olive oil. While the onion is sauteing, slice your garlic into very thin slices, but do not dice. When the onion is translucent, add garlic and mushrooms. If the garlic begins to brown or after a minute or two, add the vegan wine and reduce.
When the vegan wine is reduced by half, add the greens. It helps if you don't get them completely dry after washing; this will give them some water to steam in. Stir well and cover. After about five minutes, check them for doneness. They should be slightly wilted, but still bright green. Add the white beans and cover again. Once they are warmed through, you're set to go! Just season with salt and black pepper or chile flakes.
*If you're using very strong greens, like mustard greens or something like that, you will want to boil them first separately. Then you can add them and the beans at the same time. This will cut some of the bitterness.*