Preheat oven to 400 F.

Combine mushrooms, oil, salt and pepper. Toss to coat.

On parchment-lined sheet pan, spread mushrooms in single layer.

Roast until tender, 20 minutes. Cool.

In a food processor, puree mushrooms on medium speed for 10 seconds. Scrape the side with a rubber spatula and blend another 10 seconds.

Add mushroom mixture to beef. Mix until well blended.

Preheat flat-top griddle to 350 F or grill pan to medium-high.

Portion beef and mushroom mixture into eight 4 oz. patties.

Place on hot griddle. Cook patties 3 minutes. Turn patties over. Cook until internal temperature reaches 155F, 3 to 4 minutes.

Serve on a whole grain roll with lettuce and tomato.