Preheat the oven to 300 degrees F. In a pan on the stove top, heat ¼ cup olive oil over medium heat. Add the onions and cook until tender, stirring occasionally (about 5 mins). Then add the garlic and oregano. Cook another 2 mins, stirring regularly, until fragrant. Add tomatoes, a bit of water, bay leaf, beans, and potatoes. Season with salt and pepper. Raise the heat and bring to a high simmer for 15 minutes, stirring occasionally. Transfer to a casserole dish and pop it into the heated oven.
Keep your eye on the casserole dish. Cook until the sauce slightly thickens, and the beans and potatoes can easily be cut with side of your fork; about 35 minutes or so. (It's a good idea to check after 10 minutes or so and add a little bit of water if needed.)
Remove from oven and stir in 2 tablespoon lemon juice and chopped fresh parsley. Stir in a generous drizzle of olive oil (at least another ¼ cup).
Serve immediately with pita bread or your favorite rustic bread and some feta