Steps

1. Season the 2 mackerel fillets with salt and black pepper.
   🕒 01:48
2. Let the mackerel sit for a while, then pat dry any moisture.
   🕒 02:20
3. Cut the dried mackerel into bite-sized pieces.
   🕒 04:44
4. Lightly dust the cut mackerel with Potato Starch.
   🕒 04:57
5. Trim the ends of the 2 medium onions and cut them into wedges. This is a key technique: use larger wedges for the sweet and tender onions to give them presence.
   🕒 02:33
6. Remove the stems and seeds from the 2 bell peppers and cut them into random pieces.
   🕒 03:32
7. Trim about 1cm off the tough end of the 2 shiitake mushrooms. Cut the caps into bite-sized pieces and the stems into thin slices. Don't waste the stems; they are delicious too.
   🕒 03:55
8. In a bowl, combine [A] 150cc Water, [A] 2 tbsp Vinegar, [A] 2 tbsp Soy Sauce, [A] 2 tbsp Sugar, and [A] 1 tbsp Potato Starch. Mix thoroughly until the sugar and potato starch are dissolved. A tip: mixing these ingredients beforehand and cooking is more foolproof than making a separate slurry later.
   🕒 09:07
9. Heat 1 tbsp Vegetable Oil in a frying pan over medium heat and sear the prepared mackerel, skin-side down, until crispy.
   🕒 05:21
10. Once the mackerel is browned, remove it from the pan. You can use other white fish like sea bream, cod, swordfish, mackerel, or salmon, as well as chicken thighs or pork loin with this method.
    🕒 06:54
11. Wipe out the fish oil remaining in the frying pan after cooking the mackerel. This is important to remove any fishy odor before it oxidizes.
    🕒 07:06
12. Add 1 tbsp fresh Vegetable Oil to the frying pan and add the chopped bell peppers, shiitake mushrooms, and onions. Stir-fry.
    🕒 07:25
13. Sprinkle the vegetables with about 2 pinches of salt and stir-fry over medium heat until softened.
    🕒 07:41
14. Once the vegetables are cooked, remove them from the pan.
    🕒 08:39
15. Pour the combined [A] sweet and sour sauce mixture into the frying pan used for the vegetables. Cook over low to medium heat, stirring constantly, until thickened.
    🕒 09:39
16. Once thickened, bring the sauce to a boil. This step is crucial to prevent the thickened sauce from becoming watery again.
    🕒 10:18
17. Add 1 tsp Vegetable Oil and mix well. Adding a small amount of oil will give the sauce a glossy finish and enhance its richness.
    🕒 10:33
18. Return the seared mackerel and stir-fried vegetables to the frying pan with the sweet and sour sauce.
    🕒 11:02
19. Gently toss everything together to coat with the sweet and sour sauce.
    🕒 11:09
20. Serve on a plate. Enjoy!
    🕒 11:24