In a large saucepan of salted boiling water add spaghetti and cook until al dente.
Heat the oil in a large saucepan over medium-high heat. Add the onions and garlic and cook stirring occasionally for 3 to 5 minutes or until the onion is soft.
Add the tomatoes, cilantro, broth and salt and simmer 2 minutes. Drain pasta, add to saucepan and cook tossing until combined well. Transfer to a warm serving platter and serve hot.
Parsley is a biennial. It's true that it will grow two years in a row. But the second year it gets bitter. I recommend you replant it every year.