Heat oil in a large stainless Dutch oven. Coat lamb cubes with salt, pepper, and flour. Brown in hot oil, stirring occasionally, about 10 minutes.
Remove lamb from pan, and drain any excess oil. Add red wine, scraping bottom of pan to loosen up bits of browned meat. Add onion, celery, and garlic; cook, stirring occasionally, 10 to 15 minutes. Add lamb back to pan with vegetables. Add potatoes and next 3 ingredients; stir and bring to a low boil. Reduce heat to low; cover and simmer for 45 minutes.
Add blanched vegetables, thyme, and rosemary; stir and let simmer 30 more minutes. Garnish, if desired.
*To blanch, plunge vegetables briefly into boiling water, then into cold water to stop the cooking process.