6 beef short ribs, trimmed of fat
Kosher salt
Freshly ground black pepper
1/4 cup good olive oil
1 small fennel, fronds, stems, and core removed, large-diced
1 leek, cleaned and large-diced, white part only
1 1/2 cups chopped onion (2 onions)
4 cups large-diced celery (6 large stalks)
2 carrots, peeled and large-diced
3 garlic cloves, minced
2 tablespoons tomato paste
1 (750-ml) bottle Cotes du Rhone or other dry red wine
Fresh rosemary sprigs
Fresh thyme sprigs
1 tablespoon brown sugar
6 cups beef stock