These beans should end up fork-tender, not hard and crunchy, so they absorb all the spicy flavours.
350g (12 oz) green beans, trimmed
2 Tbsp vegetable oil
1 medium onion, peeled and chopped
2 cloves garlic, peeled and crushed
Thumb-sized piece of ginger, peeled and grated
½ tsp ground turmeric
¼ tsp chilli powder
1 large vine tomato (about 150g / 5 oz)
½ cup water
2 Tbsp chopped coriander (cilantro)
1 Plunge beans into a saucepan of gently boiling salted water and cook for 5 minutes or so, until fork-tender. Drain and refresh with cold water.
2 Wipe out pan, add vegetable oil and heat briefly, then add onion. Cook for about 7 minutes over gentle heat, until tender but not coloured. Add garlic and ginger and stir-fry for 1 minute, then add turmeric and chilli powder and ½ a teaspoon salt and cook for 1 minute more. Add tomato and water, bring to a gentle bubble, and cook gently for 10 minutes.
3 Return beans to pan and cook gently for 5 minutes more. Stir through coriander and serve.