Heat a 3-qt. sauce pan over medium-high heat.
Season lamb and dredge in the flour, shaking off any excess. Add oil to the hot pan and then add half of the cubed lamb.
Sear the lamb cubes on all sides until golden brown. Transfer to a plate. Add more oil to pan and sear the remaining lamb.
Reduce heat to medium and add in the onions and celery. Cook for 5 minutes or until the vegetables begin to soften.
Add in the garlic, bay leaf, sprigs of rosemary and tomato paste. Continue to cook until tomato paste starts to develop color.
Return lamb to the pan and coat with sauce.
Deglaze the pan with the red wine and reduce by half.
Add the stock and slowly bring to a boil. Season with a little salt and pepper, turn down and simmer for 1 hour and 15 minutes.
Add the carrots and lentils and simmer another 20 - 30 minutes until lamb, lentils and vegetables are tender.
Add more stock or water if too much liquid evaporates.
Check seasoning again. Garnish with parsley and serve with fresh, crusty bread.