Chinese Mackerel & Pickled Mustard Stew - casual rice

Ingredients

• 1 large mackerel
• 2cm knob of ginger
• half a small onion
• 2 Birdseye chillies (optional)
• salt
• ground pepper
• 2 tbsp vegetable oil
• 300g pickles sour mustard green
• 1 tbsp tomato puree – 300ml water
• 1.5 tbsp oyster sauce
• 1 tsp sugar
• cornflour mix (2 tsp cornflour + 5 tsp water) you may not need to use it all