Trim stalks of water spinach. Blanc spinach in boiling water to make it limp then place in cool or iced water. Drain completely.
Make peanut sauce in saucepan by combining all ingredients and stirring over low heat until smooth.
Fry spring onions and garlic in oil until tender. Add peanuts and then spinach and peanut sauce. Season with salt and pepper and garnish with coriander sprigs.