Sweet Potato Minestrone

1 Tsp vegetable oil
1 large onion, chopped
2 large stalks celery, chopped
2 1/2 tsp Italian seasoning
salt and pepper to taste
1 (28 ounce) can Italian-style diced tomatoes
5 cups vegetable broth
2 large sweet potatoes, peeled and diced
2 large carrots, sliced thin
6 oz green beans, cut into 1 inch pieces
5 cloves garlic, minced

Heat oil in a soup pot over medium-high heat. Saute onion, celery, Italian seasoning, salt and pepper until tender, about 5 minutes. Stir in tomatoes, with the juice, broth, sweet potatoes, carrots, green beans and garlic. Bring to a boil; reduce heat to low and simmer, stirring occasionally, until vegetables are tender, about 30 minutes.