Bring a large pot of lightly salted water to boiling. Cook pasta as package directs. Drain; keep warm.
Meanwhile, in a large skillet, heat oil over medium- high heat. Add beans and sauté for 3 minutes. Stir in onion and continue to cook for an additional 5 minutes.
Stir in tuna with its liquid, vinaigrette, olives, peppers and lemon juice. Cook to heat through. Toss with warm pasta and black pepper.