Preheat oven to 200°C. Line a large baking tray with baking parchment.
Put spring onions, garlic, lemon grass, coriander, soy sauce and some seasoning in a food processor. Whizz until finely chopped, then add mince and whizz again to combine.
Shape mixture into about 24 walnut-size balls and arrange on the lined tray. Cook for 15 to 18 minutes until golden and cook through – any juices can be poured over the meatballs when you serve.
Meanwhile, put the sugar, vinegar, chilli and 3 tbsp water in a small pan. Heat gently to dissolve sugar, then turn up the heat and bubble for 1 minute. Take off the heat and stir in the cucumber and sesame oil. Empty the sauce into a small serving bowl.
Serve meatballs with the sauce, boiled rice and seasonal vegetables.
EACH SERVING About 1 147kJ, 14g fat (5g saturated), 14g carbohydrate (14g total sugars).