Bring a medium pan of water to the boil, add the beans and cook for 4 minutes or until tender. Drain, rinse in cold water, then drain again. Transfer to a large salad bowl.
Meanwhile, heat a large non-stick frying pan without any added oil and add the SPAM®, cook over a high heat for 3 minutes, stirring occasionally until golden brown. Transfer to the salad bowl. Add the peppers to the pan and stir fry for 2 minutes.
Add the spring onions and tomatoes to the pan and stir fry for 1 minute.
Add the vinegar, and mustard to the pan and stir well.
Remove from the heat, season well with plenty of ground black pepper and transfer to the salad bowl. Toss the SPAM® and vegetables together with the salad leaves.
Serve immediately with crusty bread to mop up the juices.