In a mixing bowl combine 3 tablespoons oil, vinegar, mustard, rosemary, tarragon, and garlic cloves and whisk together.
Add lamb to marinade and toss together until each piece is evenly coated.
Refrigerate and marinate for 3 hours.
Soak 10-12 bamboo skewers in water for about 30 minutes.
Remove lamb from refrigerator and skewer cubes of lamb onto bamboo skewers until all cubes have been skewered. Season each skewer generously with salt and pepper on all sides.
Set a grill or grill pan on medium-high heat and brush the surface with remaining oil.
Grill skewers (in batches if needed) for 4 minutes on each side. Remove from heat and allow kabobs to rest, about 5 minutes.
For sauce: Combine all of the ingredients in a bowl and whisk together. Season with salt and pepper and stir together.
To serve: Pile skewers onto a platter and top with a sprinkle of sea salt flakes and cracked black pepper. Serve with dipping sauce.