Classic Thai green chicken curry

Name: Classic Thai green chicken curry
Ingredients: 1 stalk lemongrass, thinly sliced; 1 tbsp lime juice; 1 tsp whole peppercorn; 1 tsp coriander seed; ½ tsp cumin seed; 6 green bird's-eye chillies, trimmed and halved; 4 garlic cloves, peeled; 5 shallots (use Thai if possible); 3cm piece galangal or ginger, peeled and sliced; 1 rounded tsp shredded lime peel (if you can get it); 2 tbsp chopped coriander stalks; 1 tbsp chopped coriander leaves; 1 level tsp shrimp paste; 2 tbsp vegetable or sunflower oil