In a small bowl, whisk together honey, soy sauce, lime juice, water, and mustard. In a small non-stick skillet, heat oil over moderately high heat until hot but not smoking and cook salmon 2 to 3 minutes on each side, or until golden and just cooked through. Transfer salmon to 4 plates. Add honey mixture to skillet and simmer, stirring occasionally, until it reaches a glaze-like consistency. Pour the glaze over salmon and sprinkle with black sesame seeds.