Tortellini Soup with ribs

1 tablespoon olive oil 3 carrots (cut into 1/4-inch slices) 2 celery ribs (cut into 1/4-inch slices) 1 onion (coarsely chopped ( about 1 cup) 1/2 teaspoon[...]

1 large onion , chopped 2 celery ribs , chopped 2 tablespoons vegetable oil 2 (14 1/2 ounce) cans beef broth 1 cup frozen corn 1 cup sliced carrot 1 cup cut[...]

1 tablespoon olive oil 2 ribs celery, sliced 1 15-oz. can diced tomatoes, drained 1/2 teaspoon dried oregano 2 cloves garlic, minced 6 cups low-sodium chicken[...]