Start by preparing the escarole. Make sure your sink is clean and fill it halfway with cold water.
Before washing the escarole, place it horizontally on your cutting board. Cut off and discard the root end. Slice the remaining escarole bunch into three equal parts. To make smaller pieces, you can cut those in half horizontally.
Plunge the escarole into the water in the sink and swirl it around. The dirt will sink to the bottom. Transfer the escarole to a colander and give it a rinse. Let it drain while you continue with the recipe.
Rinse and peel the potatoes. Set them aside.
Peel and chop the onion. In a soup pot, heat the olive oil on medium-high. Add the onions and stir them a bit. While the onions are cooking, press the garlic (discarding the skin). Cut up the potatoes into cubes or chunks.
When the onions are tender, add the garlic to the pot and stir it in. Lower the heat a bit and let the garlic cook for about 30 seconds before adding the potatoes and vegetable stock.
Add in the bay leaf, Romano rind, red pepper flakes, salt and black pepper. Cover the pot, increase the heat to high, and let it come to a boil.
When the pot is boiling, stir in the cut escarole. Let the soup come to a boil again before lowering the heat to a simmer. Partially cover the pot by laying a wooden spoon on the edge of the pot and letting the lid rest on it. Set a timer for 10 minutes. Drain and rinse the beans.
After 10 minutes, add the drained beans to the soup. Let the soup cook for another five minutes, then check to see if the potatoes are ready. The soup is done when the potatoes are fork-tender.
Serve the soup with grated Romano (or Parmesan for a milder option). Store leftovers in a sealed container in the refrigerator for up to four days. Do not freeze this, because the potatoes won't hold up well.
Notes
Escarole comes in bunches and looks like bright green lettuce. The inner leaves are paler. You can find it at the grocery store near the heads of Romaine and endive.
Choose escarole that's not wilted or turning brown.
Try to cut the raw escarole into pieces no more than three inches long, so they'll be easier to scoop up and eat.
Be careful if using vegetarian broth instead of stock, because the broth can be quite salty. If that's all you have, don't add salt until the soup is done and you've tasted it to see if it needs any.