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Dump and Go Crockpot Mongolian Beef - Easy, Flavorful, Weeknight-Friendly

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Prep Time 10 minutes
Cook Time 4 hours
Total Time 4 hours 10 minutes
Servings 6 servings

Ingredients
  

  • 2 pounds flank steak, thinly sliced against the grain (sirloin or skirt steak also work)
  • 1/3 cup cornstarch (for coating the beef)
  • 3/4 cup low-sodium soy sauce
  • 1/2 cup brown sugar (light or dark)
  • 1/2 cup beef broth (or water)
  • 1 tablespoon fresh ginger, finely grated (or 1 teaspoon ground ginger)
  • 4 cloves garlic, minced
  • 1–2 tablespoons rice vinegar (to balance sweetness)
  • 1–2 teaspoons sesame oil (optional, for depth)
  • 1–2 teaspoons red pepper flakes or sriracha (optional, for heat)
  • 2 tablespoons cornstarch + 2 tablespoons water (slurry for thickening, if needed)
  • 4–5 green onions, sliced (for garnish)
  • Cooked white or brown rice, or noodles, for serving
  • Sesame seeds (optional, for topping)

Instructions
 

  • Prep the beef: Slice the flank steak thinly against the grain. Toss with 1/3 cup cornstarch until lightly coated. This helps the sauce cling and keeps the meat tender.
  • Make the sauce: In a bowl, whisk together soy sauce, brown sugar, beef broth, ginger, garlic, rice vinegar, sesame oil, and red pepper flakes or sriracha if using.
  • Dump and go: Add the coated beef to the slow cooker. Pour the sauce over the top and stir to separate any clumps.
  • Cook: Cover and cook on Low for 4–5 hours or High for 2–3 hours, until the beef is tender. Avoid overcooking on High, which can make lean cuts tough.
  • Thicken (if needed): If the sauce is thin, whisk 2 tablespoons cornstarch with 2 tablespoons cold water. Stir into the slow cooker and cook on High for 10–15 minutes until glossy and thick.
  • Finish: Stir in sliced green onions, saving some for garnish. Taste and adjust: add a splash more vinegar for brightness or a pinch of sugar if you prefer it sweeter.
  • Serve: Spoon over rice or noodles. Top with extra green onions and sesame seeds. Enjoy hot.