Preparation Heat oil in heavy large saucepan over medium heat. Add onions and garlic; sauté until soft, about 7 minutes. Add potatoes, tomatoes and carrot. Reduce heat; simmer until thick, stirring often, about 12 minutes. Add water and parsley. Bring to simmer. Cover; cook until potatoes are tender, about 15 minutes. Season with salt and pepper. Add mussels. Cover; simmer until mussels open, about 5 minutes. Discard any that do not open.
Preparation Heat oil in heavy large saucepan over medium heat. Add onions and garlic; sauté until soft, about 7 minutes. Add potatoes, tomatoes and carrot. Reduce heat; simmer until thick, stirring often, about 12 minutes. Add water and parsley. Bring to simmer. Cover; cook until potatoes are tender, about 15 minutes. Season with salt and pepper. Add mussels. Cover; simmer until mussels open, about 5 minutes. Discard any that do not open.