This 4-ingredient slow cooker flat iron steak is the kind of easy summer supper that practically makes itself. You start with raw beef flat iron steak, tuck it into the crock pot, and blanket it with a bright herb mixture plus just two pantry staples. Flat iron is a relatively modern cut, popularized in the early 2000s when butchers began exploring new ways to break down the shoulder. It’s flavorful, affordable, and stays tender with low, slow cooking—perfect for a hands-off meal on the first day of summer when you’d rather be outside than hovering over the stove.
Serve the sliced or shredded beef over buttery mashed potatoes, creamy polenta, or simple buttered egg noodles to soak up the herb-packed juices. For a lighter, summery spin, tuck the meat into warm tortillas with shredded lettuce and sliced radishes, or pile it onto toasted ciabatta with a smear of mayo and a handful of arugula. A crisp green salad, grilled corn, or roasted asparagus all play nicely with the garlicky herb flavors, and a light red wine like a chilled Beaujolais or a hoppy pale ale makes a friendly pairing.
4-Ingredient Slow Cooker Flat Iron SteakServings: 6
Ingredients
2 1/2 to 3 pounds beef flat iron steak, raw, thick-cut pieces
1 cup low-sodium beef broth
1/3 cup olive oil
1 packed cup finely chopped fresh parsley, cilantro, and green onion herb mix (about 1/3 cup of each), plus 3 cloves garlic, minced, tossed together
Directions
Lay the raw beef flat iron steak pieces in a single layer in the bottom of a 5- to 6-quart slow cooker. If some pieces overlap slightly, that’s fine—just keep them mostly flat so they cook evenly.
In a small bowl or measuring cup, whisk together the beef broth and olive oil until lightly emulsified. This simple mixture will keep the steak moist and create a flavorful jus as it cooks.
In a separate bowl, combine the finely chopped parsley, cilantro, and green onion with the minced garlic, stirring until you have a vibrant, slightly loose green herb mixture. It should look like a chunky, spoonable paste.
Pour the broth and olive oil mixture evenly over the steak in the slow cooker. Then spoon the green herb mixture over the top of the meat, spreading it so most of the steak is covered. The herbs will wilt and baste the beef as it cooks.
Cover the slow cooker with the lid and cook on LOW for 6 to 7 hours, or on HIGH for 3 1/2 to 4 hours, until the flat iron steak is very tender when pierced with a fork. The exact time will depend on your slow cooker and the thickness of the steak.
Once the steak is tender, taste the cooking juices and add salt and freshly ground black pepper to your liking, stirring gently so you don’t break the meat up more than you want. For a more rustic presentation, use two forks to roughly shred the steak in the slow cooker and toss it in the herb-infused juices.
Serve the beef hot, spooning some of the green-flecked juices over each portion. Any leftover meat and liquid can be cooled, then refrigerated in a covered container for up to 3 days or frozen for up to 2 months.
Variations & Tips
To keep this true to the four-ingredient spirit, I’ve built big flavor into the herb mixture, but you can adjust it to your taste as long as you don’t add more than what you consider separate ingredients. For a more classic chimichurri-style vibe, lean heavier on parsley and cilantro, and if you don’t mind bending the 4-ingredient rule at home, add a splash of red wine vinegar and a pinch of red pepper flakes. If you’re not a cilantro fan, replace it with more parsley and green onion, or even a bit of fresh basil for a softer, sweeter herbal note. You can also swap part of the beef broth for dry red wine for a richer, more robust sauce; just keep the total liquid to about 1 cup. For serving, this beef is excellent piled into toasted rolls with provolone, or folded into warm tortillas with quick-pickled onions.
Food safety tips: Use fresh, high-quality flat iron steak and keep it refrigerated until you’re ready to cook. If you prep the herb mixture in advance, store it in a covered container in the refrigerator and use it within 24 hours. Always cook the beef until it reaches at least 145°F (63°C) internally, though for this recipe you’ll likely go well beyond that for tenderness. Do not leave the cooked beef at room temperature for more than 2 hours; cool leftovers quickly, then refrigerate promptly. Reheat leftovers to at least 165°F (74°C) before serving. Avoid cross-contamination by using separate cutting boards and knives for raw meat and herbs, or thoroughly washing your tools and surfaces between tasks.
