Season lamb with salt and pepper. In a large Dutch oven or heavy pot, cook lamb over medium until some of the fat has rendered, about 4 minutes. Increase heat to high and cook, stirring occasionally, until lamb is browned on all sides, 4 minutes. Add leeks and cook, scraping up any browned bits from the bottom of the pot, until leeks are translucent, 4 minutes. Add broth.
Bring mixture to a boil. Reduce heat and simmer, partially covered, 45 minutes. Add potatoes and cook until potatoes and lamb are tender when pierced with a knife, 15 minutes. Season to taste with salt and pepper. To serve, top with parsley.
Prepare this dinner start to finish on Sunday, refrigerate, then reheat gently to serve.
This was edible, but not a "must repeat" recipe for us. Time & prep were too extensive for the payoff, and my house still stinks to high heaven.