Who needs meat? This sunny vegetarian sandwich, spread with herb mayo and layered with sliced avocado and mango, is a match made in lunchtime heaven.
In a small bowl, combine mayonnaise, cilantro, and lime juice; season with salt and pepper.
Dividing evenly, spread toasts with mayonnaise mixture. Top 4 toasts with lettuce, mango, and avocado; cover with remaining toasts. Serve immediately.