Bring a large pot of salted water to a rolling boil. Add gluten-free pasta and cook according to package directions for 8 to 10 minutes until al dente. Reserve 1/4 to 1/2 cup of pasta water, then drain and return pasta to pot.

In a large mixing bowl, combine drained tuna with pesto, flaking the tuna gently while mixing to meld flavors. Set aside.

Add warmed pasta to the bowl with tuna and pesto. Stir gently to combine, adding reserved pasta water if the mixture is too dry.

Serve warm right away or chill in the fridge for about 30 minutes for a cold salad. Garnish with fresh basil or a squeeze of lemon.