This 5-ingredient slow cooker Mongolian beef is the kind of recipe I lean on when the weekend is busy but I still want the house to smell like I’ve been cooking all day. It starts just the way the headline promises: raw flank steak strips go straight into the slow cooker, then you simply pour over four pantry-friendly ingredients and let time do the work. Mongolian-style beef, with its sweet-salty soy and garlic notes, has roots in American Chinese restaurant cooking rather than true Mongolian fare, but it fits right in on a Midwestern table—tender beef, a glossy sauce, and plenty of comfort in every bite. By suppertime, you’ll have a meal so good your friends will be asking when you’re making it again.
Serve this slow cooker Mongolian beef over hot white rice, brown rice, or buttery egg noodles so they can soak up all that rich sauce. A simple side of steamed or roasted vegetables—like broccoli, green beans, or carrots—keeps the plate colorful and balanced. If you like, add a crisp green salad with a light vinaigrette to cut through the sweetness of the sauce. Warm dinner rolls or crusty bread are very Midwestern and perfect for mopping up the extra juices. For a casual weekend gathering, set everything out buffet-style with bowls of rice, the beef, and a big platter of vegetables so folks can help themselves.
5-Ingredient Slow Cooker Mongolian BeefServings: 6
Ingredients
2 pounds flank steak, sliced into thin strips against the grain
1 cup low-sodium soy sauce
3/4 cup packed brown sugar
1 tablespoon minced garlic (about 3 cloves)
1/2 cup sliced green onions (plus extra for serving, optional)
Directions
Lay the raw flank steak strips in an even layer on the bottom of a 4- to 6-quart slow cooker. If some pieces overlap, that’s fine; just spread them out as best you can so the sauce can reach everything.
In a medium bowl or large measuring cup, whisk together the low-sodium soy sauce, brown sugar, and minced garlic until the sugar has mostly dissolved and the mixture looks like a dark, glossy liquid.
Pour the soy-garlic mixture evenly over the raw flank steak strips in the slow cooker, making sure all the meat is moistened. Sprinkle the sliced green onions over the top. At this point it should look like raw beef strips sitting in a dark sauce with green bits scattered over them.
Cover the slow cooker with the lid and cook on LOW for 4 to 5 hours, or until the flank steak is very tender and easily pulls apart with a fork. Avoid lifting the lid too often, as that lets out heat and can lengthen the cooking time.
Once the beef is tender, give everything a good stir so the strips are well coated in the thickened sauce and the green onions are evenly distributed. If the sauce seems too strong, you can stir in a few tablespoons of water to mellow it.
Taste the sauce and adjust if needed by adding a pinch more brown sugar for sweetness or a splash of soy sauce for saltiness. Serve the Mongolian beef hot over rice or noodles, spooning plenty of sauce over the top. Garnish with additional sliced green onions if you like.
Variations & Tips
If you prefer a little heat, stir in 1/4 to 1/2 teaspoon of crushed red pepper flakes along with the garlic for a gentle kick that doesn’t overwhelm the sweetness. For a slightly lighter version, you can use reduced-sodium soy sauce as written and trim any visible fat from the flank steak before slicing. If you want the sauce thicker without adding more ingredients, remove the slow cooker lid for the last 20–30 minutes of cooking and let some of the liquid evaporate, stirring occasionally. To stretch the meal for a crowd, stir in lightly steamed broccoli florets or snap peas during the last 30 minutes of cooking so they warm through in the sauce without getting mushy. If flank steak is unavailable, you can use thinly sliced sirloin or round steak, keeping the same method and timing. For food safety, always slice the raw flank steak on a clean cutting board using a clean knife, and wash your hands, board, and knife thoroughly with hot, soapy water before handling any other ingredients. Make sure your slow cooker is set to LOW and that the beef cooks until it is fully tender and reaches a safe internal temperature of at least 145°F (63°C). Refrigerate leftovers within 2 hours in shallow containers, and reheat until steaming hot before serving again.
