Peel and slice the carrots and celery. Dice the onion and peel the potatoes. In two separate pots place the lamb into one and the vegetables into the other. Cover both with water.
In the vegetable pot, add the bouillon, herbs and a pinch of salt and pepper to taste. Bring to the boil and cook 3 quarters of the way through. In the lamb pot add some rosemary and thyme and boil until the lamb is tender.
Strain half the liquid from the lamb and add the contents of that pot to the vegetable pot – covering with more water if necessary. Cook out the vegetables fully and season the stew.
If you prefer a cloudy stew rather than a broth add a little mashed potato.