Penne Nicoise - cooking recipe

Ingredients

1 lb green beans, cut into 1 inch lengths (about 4 cups)
1 lb red potatoes, cut into 1 inch pieces (about 3 cups)
1 lb penne pasta
2 tablespoons olive oil
1 medium yellow onion, thinly sliced
2 garlic cloves, minced
1 lb plum tomato, ripe, chopped (about 3 cups)
1 cup kalamata olive, pitted and chopped
2 tablespoons balsamic vinegar
1/2 teaspoon fresh ground black pepper
salt, to taste

Preparation

Bring large pot of salted water to boil and add green beans and potatoes. Return to boil and add pasta. Cook, stirring occasionally, until the pasta is al dente, about 11 minutes or according to package directions.
Meanwhile, in small skillet heat the olive oil over medium heat. Add onion and garlic and cook, stirring often, until onion is soft, about 5 minutes.
Remove from heat and stir in tomatoes and olives and set aside.
Drain the pasta, beans and potatoes, reserving 1/2 cup of pasta water. Transfer to serving bowl. Add the tomato mixture, vinegar, pepper and salt and toss to mix.
If pasta seems too dry add reserved pasta water as needed, a little at a time.