By now your vegetables should be nicely sautéed. Stir in the oregano, tomatoes, beans, and tomato paste, and let simmer for 2-3 minutes.
Stir in the swiss chard or kale, then place the slices of bread on top of the soup, arranging them in a single flat layer so they do not overlap. I like to cut the slices of bread in half to make this easy.
Usually red onions are placed on top of ribollita, but I prefer white, so I used white. I used swiss chard, but you could opt to use kale or cabbage. Black cabbage is traditionally used. I would recommend against using spinach since it doesn't hold up as well and may get too soggy and fall apart. Traditionally this soup is made in a ceramic pot, but any oven-safe pot will work.