Place a large frying pan or wok over a medium heat. Add the sesame seeds (there's no need to spray the frying pan with low-calorie cooking spray), and toast lightly for about 1 minute, stirring, until golden. Watch carefully as the sesame seeds can burn quickly. Transfer to a plate and set aside.
Spray the frying pan with low-calorie cooking spray and place over a medium heat. Add the garlic puree, ginger puree and chilli. Stir-fry for about 30 seconds until combined. Increase the heat to high and add the frozen beans, stirring and constantly moving the beans around the frying pan or wok. Stir-fry for about 4 minutes, until tender but not soft. The beans should retain a little crispness.
Add the soy sauce and toasted sesame seeds and stir in. Serve at once with a main dish of your choice.