Bring a large pot of salted water to a boil over high heat. Add the pasta and cook until tender but still firm to the bite, stirring occasionally, about 8 to 10 minutes. Drain pasta reserving 1 cup of the cooking water. Transfer the hot pasta to a large bowl and add the ricotta cheese. Toss to combine.
Meanwhile, in a large, heavy skillet, warm the olive oil over medium-high heat. Add the green beans, garlic, salt, and pepper and saute for 4 minutes. Add 1 cup of the pasta cooking liquid and continue cooking until tender, about 4 more minutes. Add the pasta with ricotta to the pan with the green beans and toss to combine. Add the tomatoes and gently toss. Transfer to a serving plate and top with lemon zest. Serve.