Bordeaux-Style Broiled Striploin

Ingredients

• • 1 large onion, cut into thin wedges
  • 8 oz (227 g) white button mushrooms, halved
  • 3 tablespoons (45 ml) olive oil
  • 1/4 cup (60 ml) butter, softened
  • 1 large shallot, finely chopped
  • 2 large beef striploin steaks, about 1 1/2-inch (4-cm) thick
  • Salt and pepper