I've never made mongolian beef and I have no idea if this is the recipe you are looking for. But I found it and thought I would share it with you.
Mongolian Beef
Serves : 4
Prep. Time : 1:30
1 Lb. sirloin steak - fat trimmed, sliced thin
2 Tbls. soy sauce
2 Tbls. corn starch
1 1/2 Tbls. peanut, sesame, OR vegetable oil
2 tsp. sugar
1/2 tsp. salt
2 dashes white pepper
1 Tbls. peanut, sesame, OR vegetable oil
4 cloves garlic - minced
2 tsp. ground ginger
8 oz. can sliced water chestnuts - drained
6 green onions - sliced lengthwise
3 Tbls. soy sauce
-Combine meat, soy sauce, cornstarch, oil, sugar, salt, and pepper and refrigerate at least 1 hour.
-In 375 degree wok, cook garlic and ginger in oil for 3-5 minutes.
-Add remaining ingredients, including meat mixture.
-Stir fry for 5-10 minutes, or until meat is cooked through.
NOTES : Serve over rice and use chopsticks to eat.
Got that one here:
http://recipes.robbiehaf.com/M/247.htm
Here's another one from cooks.com:
MONGOLIAN BEEF
1 lb. sirloin tip steak
1 med. onion (sliced)
1 bunch green onions (cut 2 inches long)
6 to 8 pieces small dried chili peppers
2 to 3 slices fresh ginger root
MARINADE:
1 tbsp. dark soy sauce
2 tbsp. rice wine
2 tbsp. oyster sauce
1 tbsp. corn starch
3 to 4 slices ginger root
Marinade 30 minutes.
Using wok, pour 1/4 to 1/3 cup peanut oil. When oil is hot, add chili peppers and ginger root. When ginger root and peppers turn brown, remove from pan. Stir fry meat. Save extra juice from marinade.
Set aside meat. Stir fry onions and green onions. Add extra juice and meat. Stir together well. Serve hot with rice or over bed of fried bean thread.
Hope one of those works for you.