Pat lamb dry with paper towels. Toss lamb cubes with flour in medium-sized bowl. Shake off excess flour and set aside on a wire rack.
Pour oil into Dutch oven set over medium-high heat. When oil is shimmering, add lamb. Cook lamb until browned on each side, about eight minutes total. Remove lamb to a plate and set aside.
Add shallots, leeks, garlic, and thyme to Dutch oven. Cook, stirring often, until leeks are lightly browned, about four minutes.
Add stock, white wine, lemon juice, and lemon zest to pot. Scrape up any browned bits from bottom of Dutch oven with wooden spoon. Season with a pinch of salt and pepper, and return lamb to Dutch oven.
Turn heat to high and bring to boil. Reduce heat to a simmer, and partially cover. Cook, stirring frequently, until lamb is very tender, 45 minutes to an hour.
Season to taste with salt and pepper. Sprinkle with chopped parsley and serve with boiled potatoes.