Spray a large frying pan with low-calorie cooking spray and place over a medium heat. Add the onion and garlic and cook gently for 8-10 minutes, until golden and softening.
Add the bacon and Cajun seasoning, stir and cook for 3-4 minutes until the bacon is cooked.
Increase the heat and add the frozen beans and lemon juice (there's no need to defrost the beans first). Stir-fry for 5-6 minutes, until the beans are tender with a little 'bite', bright green and piping hot throughout.
Taste and season well if needed. Serve with a main dish of your choice!