Start by preparing your slow cooker. Place the sweet onions, minced garlic, and olive oil at the bottom of the slow cooker. Mix them together, ensuring that the vegetables are well coated in the oil. This will help them soften and release their flavors as they cook.
Next, add the thinly sliced lean round sirloin steak to the slow cooker. This cut of meat is perfect for slow cooking as it becomes tender and juicy over time. Add in the butter, and sprinkle with kosher salt and pepper. Stir everything together to combine the flavors.
Now it's time for the fun part! Add the sliced mushrooms and green bell peppers to the mix. Their vibrant colors will brighten up the dish and add extra layers of flavor.
Pour in the low-sodium beef broth and soy sauce. These ingredients will create a savory sauce that seeps into the beef and vegetables, infusing everything with delicious flavors.
Cover the slow cooker with its lid and set it to cook on low for about six to eight hours. Alternatively, you can cook it on high for five to six hours. The long cooking time allows the ingredients to meld together beautifully, creating an irresistible filling.
When the cooking time is up, check the tenderness of the beef— it should be fork-tender and easy to shred. Stir everything gently to combine the ingredients once more.
To assemble your sandwiches, take a whole-wheat sub roll and scoop a generous portion of the cheesesteak mixture into it. Top with a slice of provolone cheese if desired, then place the sandwich under the broiler for a few minutes until the cheese melts and the roll is slightly toasted.
Once the cheese is melted and bubbly, remove the sandwich from the oven. Let it cool for a minute before taking a big bite!
Enjoy your Slow Cooker Philly Cheesesteaks with your favorite sides or simply on their own. They're sure to be a hit!
