Start by bringing a large Dutch oven or pot to a medium-high heat and add the lamb pieces. Brown thoroughly, in batches if needed, you want the fat to render as this will deliver a flavourful dish.
Once browned, add the dice onion, tomato paste, mixed dried herbs, garlic and chili. Sauté for 2 minutes or until the paste starts to stick to the base of the pot.
Add the crushed tomatoes, water, white wine vinegar and green beans. Mix well. Top with the quartered potatoes and cover. Simmer for 1 hour on a medium-low heat. Note: resist stirring the stew during this hour. You may add up to an additional 200ml water if the stew becomes a tad too thick.
Remove the lid and gently stir the stew. Cover again and continue simmering for 30 minutes at low-medium heat.
Remove the lid, gently stir and allow to simmer uncovered for another 30 minutes, ensuring the gravy thickens to your liking. The lamb should be tender and falling of the bone.
Season with salt and coarsely ground pepper to your taste and serve with fluffy white rice and or freshly buttered bread.