Pick over and wash lima beans, and soak them in water to cover at least 6 hours or overnight. Drain off the soaking water and place the limas in a large stewpot with fresh water. Bring to a boil, then lower the heat and simmer gently for 1 hour. Scrub the potatoes and carrots. Cut the potatoes in 1 cm dice. Cut the carrots in half lengthwise, then crosswise into 1 cm slices. Add the potatoes and carrots to the limas. While they are cooking, saute the onion in 1 tablespoon of oil until golden brown. Crush the fennel seed lightly in a mortar and add it along with the thyme, marjoram, garlic, and 2 tablespoons of water to the onion. Cook over low heat for 3 minutes to blend the flavors. Add the wine and simmer until the liquid is reduced a little. Scrape the onion mixture into the bean mixture and return the skillet to the burner. Saute the mushrooms in the remaining tablespoon oil until they turn golden around the edges. Add the mushrooms to the stew, adding more water if necessary to keep the stew from sticking. Add the diced fennel bulb, bay leaf, and tamari, and simmer about 10 minutes or until the fennel bulb is just tender. Add the lemon and serve immediately.