Bring a pot of salted water to a boil. Cook your pasta following the package instructions. Reserve 1/2 cup of hot pasta water before draining the pasta.

While the pasta cooks, mash the avocado in a large bowl. Stir in garlic, lemon juice, salt, and pepper. Add ¼ cup of the reserved pasta water to the avocado mixture and stir.

Add the cooked pasta, tomatoes, and green onion to the bowl. Toss everything together until the sauce evenly coats the pasta. Add a little more pasta water to thin out the sauce if needed.