In a large casserole dish, heat some oil and gently fry the sausages all way round, turning them regularly.
Meanwhile, thinly slice the onion and fennel, chop the garlic and dice the carrot.
When the sausages are golden, transfer them to plate. Add more oil to the pot if needed, then sauté the onion and fennel over low heat for 8 minutes or so.
When tender, add the carrot and garlic, and scatter the dried herbs over the veggies. Stir for a minute, then add the wine, if used, and let it sizzle for a minute. Add the chicken stock.
Bring to a boil, cover with a lid, then turn down the heat again and cook for 10 minutes.
Add the broad beans and cook for another 5 minutes, over medium heat and without the lid, so that the stew can reduce further. Add the lemon juice too.
Add the sausages to warm through.
When the beans are cooked and you have a silky, thick sauce, turn off the heat and stir in the lemon zest and the chopped parsley.
Serve warm.