For the tamarind sauce
- 3 tbsp sunflower or rapeseed oil
- 1 onion, finely chopped
- 3 garlic cloves, finely grated
- 20g/¾oz fresh ginger, finely grated
- 1 red or green chilli, finely sliced
- 2 tsp garam masala
- ½ tsp ground turmeric
- 1 tbsp tomato purée
- 2 tbsp ready-made tamarind paste (or purée, see tip below)
- ½ tsp flaked sea salt
- ½ tsp caster sugar
For the duck
For the tamarind curry sauce, heat 2 tablespoons of oil in a medium non-stick frying pan and fry the onion, garlic and ginger over a low heat for 8 minutes, or until well softened, stirring regularly.
Add the rest of the oil, chilli, garam masala and turmeric. Cook for 2 minutes, stirring constantly, then add the tomato purée, tamarind paste (or purée), salt and sugar. Cook for 2 minutes, stirring. Add 200ml/7fl oz of cold water and bring to a simmer. Cook for 5 minutes, stirring occasionally.
Transfer the mixture to a heatproof jug and blend with a stick blender until smooth. (You can also leave to cool a little and then transfer to a food processor or blender and blitz until smooth.) Adjust the seasoning to taste, adding a little more salt if needed. Set aside.
For the duck, heat the oil in a clean non-stick frying pan over a medium-high heat. Season the duck with a little flaked sea salt and add to the pan. Stir-fry for 2–3 minutes, or until lightly coloured on all sides. Add the sauce to the duck and bring to a simmer. Cook for 3 minutes, stirring constantly. Scatter the spring onion over and serve.
If using a block of tamarind instead of a ready-made paste, place 25g/1oz seedless tamarind pulp in a bowl and cover with 100ml/3½fl oz just-boiled water. Leave to stand for 15–20 minutes, or until softened, then pass through a fine sieve to make roughly 2 tablespoons of tamarind purée.