Bring a large pot of salted water to a boil. Add orzo and cook for 8-10 minutes until al dente. Drain and rinse with cold water.

Blanch green beans in boiling water for 2-3 minutes. Transfer to ice water, then drain.

In a mixing bowl, combine orzo, tuna, tomatoes, and green beans. Add red onion.

Drizzle with olive oil and lemon juice. Toss gently to combine. Season with salt and pepper.

Serve immediately or chill in the fridge for an hour.