Red Beans and Rice

Name: Red Beans and Rice
Ingredients: 2 tablespoons vegetable oil; 1 medium onion chopped; 1 green pepper seeded and chopped; 3 stalks celery chopped; 12 ounces Andouille Sausage chopped; 3 cloves garlic minced; 1/2 teaspoon dried oregano; 1 1/2 teaspoons Cajun seasoning; 2 cans (15.5 oz) red beans drained; 2 cups low sodium chicken broth; 1 can (14.5 oz) diced tomatoes (optional); 1 cup long grain white rice (uncooked)