Rinse the beans and put them in a bowl, covering them amply with cold water. Let soak at least 8 hours or, ideally, overnight.
Heat the oil in a heavy pot or pressure cooker over medium flame. Stir in the onion, celery and garlic, and sauté until the onions soften, 5 minutes or so.
Add the tomatoes, water, sage, bay leaf and pepper. Drain the soaked beans, rinse again, and add them into the pot.
For pressure cooker: Bring the cooker to pressure and cook 10 to 12 minutes. Remove from the heat and allow the pressure to release naturally, 10 to 15 minutes.
For regular stovetop cooking: Bring to a boil, lower the heat so the liquid simmers just below a boil, and cook until the beans are tender, 2 to 2 ½ hours. (Check the pot every so often and top with more water if the level is getting low.)
Remove the bay leaf and stir in the salt. Taste and season with more salt and pepper if needed.
Serve over rice and cooked kale or collards or chard, something green.