In a roaster or wide dutch oven, fry the bacon lardons until almost crisp.
Add the onion, leeks, and cumin seeds, and saute until the onions soften and begin to turn clear. (Add a drizzle of olive oil if more fat is needed.)
Add the minced garlic. Sauté for 1 more minute.
Add the cans of beans – including the juices, the herb springs, the seasoning mix, and stock. (And potatoes if using.) Lightly salt and add fresh ground pepper to taste.
Remove from heat and add the lamb.