Cut the lamb shoulder into 1-inch cubes and chop the red bell pepper and red onion into similar sized pieces.
In a small bowl, whisk together 0.5 tbsp of the olive oil, 0.5 tbsp of the lemon juice, the dried oregano, sea salt, and black pepper to create a marinade.
Place the lamb cubes and vegetable pieces into a bowl, pour the marinade over them, and toss thoroughly to coat; let marinate for 15 minutes.
Thread the marinated lamb and vegetables onto two skewers, alternating between the meat and the produce.
Preheat a grill or grill pan to medium-high heat and cook the kebabs for 8 to 10 minutes, turning occasionally until the lamb is browned and the vegetables are tender.
While the kebabs cook, finely mince the mint, parsley, and garlic, then combine them in a small bowl with the remaining 0.5 tbsp of olive oil, 0.5 tbsp of lemon juice, and red pepper flakes.
Remove the kebabs from the heat and serve immediately with the vibrant mint-herb sauce drizzled over the top.