Combine garlic, ginger, chilli, lemongrass, green onions and coriander in a food processor. Process until finely chopped. Transfer to a bowl. Add mince and egg. Season with salt and pepper. Using clean hands, mix until well combined. Using 2 heaped tablespoons mixture at a time, roll mixture into 16 balls. Flatten slightly. Place rissoles on a plate. Cover and refrigerate for 30 minutes, if time permits.
Preheat a greased barbecue plate on medium-low heat. Spray both sides rissoles with oil. Cook, turning occasionally, for 12 to 15 minutes or until cooked through.
Using a vegetable peeler, peel long, thin strips from cucumbers. Spoon rice into bowls. Top with rissoles, cucumber and sweet chilli. Serve.