Grilled Portobello Mushroom Sandwiches with Basil Aioli

The portobello mushroom has become the fin de siècle “steak,” a grilled vegetable alternative to beef. The broad fleshy mushroom cap has a rich meaty flavor, and luckily, portobellos are available at most supermarkets and specialty food shops. To this, add a fresh basil-flavored aioli (French garlic mayonnaise) and you’ve got a sandwich that tap dances on your taste buds!