No buns? No big deal! Our saucy, slightly sweet meat mixture is just as yummy spooned over juicy portobello mushroom caps—and is actually much easier to eat with a knife and fork!
Serves 4
Prep: 30 minutes
Closed Pot: 25 minutes
Total: 55 minutes
4 medium portobello mushrooms (3 to 4 ounces each)
3 green onions
1 pound ground beef
1 small red bell pepper, chopped
1 small stalk celery, thinly sliced
½ cup Whole30-compliant beef broth or Beef Bone Broth (page 294)
⅓ cup Whole30-compliant tomato paste
2 to 3 tablespoons balsamic vinegar
2 cloves garlic, minced
1 teaspoon dried oregano
½ teaspoon salt
½ teaspoon black pepper
¼ cup chopped fresh parsley
Use a damp cloth or paper towel to wipe the mushrooms. Remove the stems from the mushrooms and chop; set aside. Using a small spoon, scrape the gills from the mushroom caps and discard. Set the mushrooms aside. Thinly slice the green onions; separate the white and green parts.
On a 6-quart Instant Pot, select Sauté and adjust to Normal/Medium. Add the chopped mushroom stems, white parts of the green onions, the ground beef, bell pepper, and celery. Cook, stirring with a wooden spoon to break up the meat, until the meat is browned, about 10 minutes. Press Cancel. Drain any fat.
Add the broth, tomato paste, 2 tablespoons of the vinegar, the garlic, oregano, salt, and pepper to the meat mixture. Stir until well combined. Place the mushroom caps, stemmed sides down, over the meat mixture, overlapping them slightly, if needed. Lock the lid in place.
Select Manual and cook on high pressure for 3 minutes. Use natural release.
Transfer the mushrooms to serving plates, stemmed sides up. Stir the meat mixture. If desired, stir in the remaining 1 tablespoon vinegar. Spoon the meat mixture on the mushrooms. Sprinkle with the reserved green onion green parts and the parsley.