Burger With Mushrooms and Radicchio

Ingredients

• 0.8 teaspoon pepper black divided freshly ground
• 1.3 pounds ground sirloin 
• 8 ounce hawaiian rolls whole-wheat split
• 0.3 teaspoon kosher salt 
• 1 pound mushrooms mixed trimmed
• 1 pound mushrooms mixed trimmed
• 1 tablespoon olive oil 
• 1 small head radicchio thinly sliced into thin rings

Equipment

• frying pan
• kitchen thermometer

Directions

1. In a large nonstick skillet, heat oil over medium-high heat.
2. Add mushrooms and 1/4 teaspoon each salt and pepper, and cook, stirring, until tender and golden (4-6 minutes).
3. Transfer mushrooms to a plate. Wipe out skillet; reserve.
4. With clean hands, form meat into 4 patties; sprinkle remaining 1/2 teaspoon pepper over both sides of burgers. Return skillet to medium-high heat; cook burgers until medium (5-6 minutes per side), or until a meat thermometer inserted in the center reads 16
5. Place 1/4 of the radicchio slices, then burgers, on bottom buns; divide mushrooms among burgers and top with other half of bun.