Greg's sweet and sour fish

I've been making this dish since my student days. In those days, it was one of the most complicated dishes I made, but it no longer cause quite the stress that it did in those days, at least partially because I have simplified the recipe (made easier by the availability of microwave ovens).

The biggest issue with this dish is the balance between sweet and sour in the sauce. In particular, the strength of commercially available vinegar can vary considerably. In case of doubt (some vinegar, notably that from ALDI, doesn't specify the strength), assume between 4% and 5%. A further issue is that the sauce isn't stable: the vinegar hydrolyzes the sugar, converting it to less-sweet glucose and fructose, so the vinegar should be added just before serving.

The recipe originally came from “Chinese Food”, by Kenneth Lo, who specified carp, and that it should be deep-fried. This version dates from 2009, and I've reconsidered it in August 2011, June 2017, August 2023 and November 2023 without coming to a definitive replacement. This revision dates from 29 March 2024.

Ingredients

Preparation time:		60 minutes

quantity	ingredient	step
10 g	dried tree fungus (mushrooms)	1
	OR	1
50 g	fresh oyster mushrooms	1

400 g	fish fillet	2
5 g	salt	2
	wheat flour	2

20 g	spring onion, chopped	3
15 g	garlic, crushed	3
100 g	sweet red capsicum	3
50 g	bamboo shoots	3
80 g	peas	3

90 ml	water	5
20 ml	soya sauce	5
40 ml	dry sherry or rice wine	5
4 g	chicken stock powder	5
5 g	salt	5
25 g	tomato purée	5
25 g	sugar	5
10 g	cornflour	5

65 ml	Chinkiang vinegar, 5.5% (3.6 g acetic acid)	6
	OR	6
72 ml	vinegar, 5%	6
	OR	6
80 ml	vinegar, 4.5%	6
	sesame oil	6
	coriander leaf, chopped	6

Preparation

If using dried tree fungus, soak in water for about 20 minutes to soften it. Cut into fine strips. Otherwise cut the oyster mushrooms into slightly thicker strips (about 4 mm thick).
Cut the fish into about 12 pieces. Rub it with salt and leave for a few minutes. Heat deep fryer to 180°.
Fry the onion, garlic and capsicum in a pan. When a little softened, add the bamboo shoots, peas and drained fungus.
While the vegetables are frying, roll the fish in flour and then deep fry until cooked, about 5 minutes.
Add the sauce ingredients to the vegetables and bring to the boil. Stir until thickened.
Place the fish in a serving dish. Add vinegar and sesame oil to the sauce and mix well. Pour over the fish and garnish with coriander leaf. Serve.