Place the pesto in a bowl and mix in the lemon juice. Add the tuna to the bowl and break it up into flakes with a fork.
Add the scallions, red pepper, tomatoes and pasta to the bowl, then toss the salad to evenly coat it with the sauce. Season the salad with salt and pepper, to taste.
This is one of many “Yum-o!” recipes – it’s good and good for you. To find out more about Yum-o!, Rachael’s nonprofit organization, go to www.yum-o.org.