French Dip Panini

INGREDIENTS

• 1 bone-in standing beef rib roast, about 3 lb.
• Kosher salt and freshly ground pepper, to taste
• 2 1/2 cups beef broth
• 1 tsp. vegetable oil
• 1 shallot, finely chopped
• 1/4 cup water
• 1 fresh thyme sprig
• 4 French sandwich rolls, split horizontally
• 2 Tbs. unsalted butter, melted
• 1/2 cup caramelized onion (from 1 yellow onion)
• 8 oz. provolone cheese, thinly sliced
• 1/2 bunch watercress