1.   Heat up 2 tbsp retained mackerel oil in the hot wok, saute the garlic and ginger till fragrant. Add fermented salted black beans and
      mackerel, stir well until aromatic.

2.   Add in Chinese broccoli, water and seasoning, stir-fry briskly at high heat until well combined. Lastly, thicken the sauce with a little
      cornstarch solutions. Remove from heat, serve at once.