Set broiler on high. Cut bread into slices about 1/2-inch thick. Arrange them on a baking tray and place them on the top rack. Broil for several minutes, until the bread is golden brown. Flip slices over and brown the other sides for another couple of minutes, watching carefully so as not to burn. Remove the tray and set aside.
Heat 2 tablespoons of oil in a large pan over medium heat. Add beans, oregano, crushed red chili flakes, minced garlic, and salt. Cook until heated through, about 5 minutes, while mashing gently with a fork, leaving some beans whole. Stir in roasted red pepper and spinach. Add the water and stir again. Cover the pan and cook for several minutes more, until the spinach is mostly wilted. The mixture should be loose; add a little more water, if necessary. Remove cover, squeeze lemon over everything and stir. Remove from heat and keep covered.
Rub the remaining 2 cloves of garlic over the one side of each slice of bread. Arrange bread on a platter or on plates. Spoon the spinach and beans onto the bread. Drizzle with remaining oil. Sprinkle with pepper, garnish with chopped herbs and serve.