Dump-and-Go Crockpot Mongolian Beef

4 h 45 min | easy | low-fat

Recipe by Eunice Published Mar 23, 2026

Prep Time	Cook Time	Total Time
15 min	4 h 30 min	4 h 45 min

Rate/Review

Introduction

Dump-and-go Crockpot Mongolian Beef is sweet, savory, and wonderfully tender with a rich soy-garlic sauce.

It's a great weeknight dinner or easy meal-prep option, served over rice for a takeout-inspired family meal.

Prep mode (keeps screen awake)

Add beef to the slow cooker

Place the sliced beef in the slow cooker and separate any pieces that are stuck together.
Pat the beef dry first if it looks wet from packaging.
Mix and pour the sauce

Whisk the sauce ingredients, except the cornstarch, extra water, and green onions, in a bowl.
Pour the mixture over the beef and toss gently to coat.
Cook until tender

Cover and cook on low for 4 to 5 hours or on high for 2 to 3 hours.
The beef should be tender and easy to pull apart with a fork.
Thicken the sauce

Whisk the cornstarch and 3 tablespoons water in a small bowl until smooth.
Stir the slurry into the slow cooker during the last 20 to 30 minutes.
Cover again and cook until the sauce turns glossy and lightly thickened.
Finish and serve

Stir in most of the green onions, then taste and adjust the heat if needed.
Serve hot over steamed rice or noodles, and top with the remaining green onions.

Replace beef with boneless chicken thighs: Chicken thighs stay juicy in the slow cooker and absorb the sauce well. The dish tastes a bit lighter, yet still rich and savory.
Replace brown sugar with honey: Honey gives the sauce smoother sweetness and a shiny finish. Use a little less, since honey tastes sweeter than brown sugar.
Replace green onions with crispy shallots and chopped chives: This swap adds crunch and a deeper onion note. It also gives the bowl a fun, takeout-style finish.

Choose the right cut: Flank steak, sirloin, or skirt steak work best here. Their fibers soften nicely when sliced thin and cooked gently.
Pat the beef dry: Dry surfaces help the sauce cling and keep the slow cooker sauce from getting watered down. That small step also improves the final texture.
Add the slurry late: Cornstarch can lose strength during long cooking. Stir it in near the end for a glossy, silky sauce.
Taste before serving: Soy sauce brands vary a lot in saltiness. Add a small splash of water if the sauce tastes too strong.
Rest the sauce briefly: Let the finished beef sit on warm for 5 minutes before serving. The sauce settles and thickens a bit more.

^* Approximate, per serving.
Data source: USDA FoodData Central.

Why is my sauce still thin after adding the slurry?: Make sure the cornstarch was fully dissolved before it went in. Then cook uncovered or partly uncovered for several minutes to reduce the sauce.
Why did my beef turn chewy?: The slices may have been too thick or cut with the grain. High heat for too long can also tighten the meat.
Can I put everything in the slow cooker the night before?: Yes, if the beef stays refrigerated in the insert or another container. Add the slurry later, since cornstarch thickens best near the end.
Can I use frozen beef?: Thaw it first for even cooking and better texture. Frozen meat releases extra water and can thin the sauce.
How can I make it less sweet or more spicy?: Cut the brown sugar by 1 or 2 tablespoons for a less sweet sauce. Add extra red pepper flakes or chili-garlic sauce for more heat.