This messy sandwich uses the meatiest of all vegetables: the Portobello, a thick juicy mushroom that’s not at all like the slimy canned ones I came to fear in childhood. Grilled with a bit of garlic and balsamic, a smoky umami infuses the entire mushroom.
This is a recipe for ambitious home cooks: there are multiple steps, and you’ll dirty a sauté pan, a sauce pan, and a paella pan—if you have one. You’ll chop, sauté, and grill. And, the payoff is huge.