Preheat oven to 375°. In a Dutch oven, heat oil over medium heat. Add lamb and onion; cook and stir until meat is no longer pink. Stir in flour until blended. Gradually add broth. Bring to a boil; cook until thickened, 1-2 minutes, stirring to loosen browned bits from pan. Add carrots, leeks, 1 tablespoon…