1 tablespoon good olive oil
2 pounds beef oxtails
Kosher salt and freshly ground black pepper
2 cups chopped leeks, white and light green parts (2 leeks)
2 cups (1/2-inch) diced carrots (4 carrots)
1 cup chopped yellow onion
1 cup (1/2-inch) diced celery (2 stalks)
2 garlic cloves, minced
2 sprigs fresh thyme leaves
3 bay leaves
10 cups canned beef broth
1 cup pearled barley