Associated Press photo by Matthew Mead -- Open-faced Stuffed Portobello Sandwich

Like Philadelphia itself, there is a lot to love about the city’s signature sandwich — the cheesesteak.

But that delicious combination of beef, onions and cheese isn’t the sort of thing you want to eat everyday. So I decided to see if I could make a healthier sandwich.

I swapped out the beef for that most steaklike of mushrooms, the portobello, and filled the roomy cap of it with roasted red peppers, grilled scallions, olives and mushroom trimmings, then topped with melted provolone cheese, and a little bit of rosemary mayonnaise.

Finally, the whole thing is set on a slice of grilled rustic bread. It may be meatless, but it is chock-full of nutrients.

To clean these big mushrooms, remove the dark gills on the underside, lightly scraping them out with a teaspoon. Then rinse the cap on both sides under cold running water to remove any dirt.

Pat the caps dry so they can absorb the marinade.

Topping-wise, I’ve gone the Mediterranean route, but you can substitute the toppings of your choice. Maybe you’ll want to grill and chop up some complementary mushrooms — like shiitake or oyster — or you’ll top it off with grilled broccoli, asparagus or onions. If you’re not crazy about provolone, swap in thin slices of mozzarella, cheddar or Italian fontina.

Finally, if don’t like mayo, Dijon mustard works very nicely.

However you customize it, try adding this super-satisfying vegetarian ringer to the menu the next time you’re grilling and see if you don’t win some converts.

Sara Moulton was executive chef at Gourmet magazine for nearly 25 years, and spent a decade hosting several Food Network shows. She currently stars in public television’s “Sara’s Weeknight Meals” and has written three cookbooks.