Heat oil in a large saucepot with a lid over medium heat. Add onions, carrots, red pepper and celery; cook, stirring occasionally until softened about 5 to 10 minutes. Add garlic, cumin and oregano; cook, stirring, until fragrant, about 1 minute. Add water and beans; bring to a simmer. Cover and simmer over low heat, stirring occasionally about an hour. When the beans have simmered, add the tomatoes, barley and salt. Simmer, partially covered, stirring occasionally, until beans and barley are tender and chili has thickened, about 45 minutes more. Season the chili with vinegar, pepper, and salt. Makes 6-8 servings.