Place the potatoes in a large pan of boiling water and cook for 8-10 minutes until tender.
Add the green beans and cook for a further 2 minutes before draining.
Transfer the potatoes and green beans to a large bowl.
Add the cannellini beans, red onion, tuna and herbs.
In a small bowl mix the oil, pesto, lemon juice and season.
Fold through the salad and spoon onto plates to serve.
Our thanks to the Potato Council for providing this recipe.