Beef lo mein is one of my all time favorites. It's flavorful, it's fresh, it's easy, and it just makes for some good old family time around the table for us. Lo mein is just FUN to eat no matter how old you are. The secret to a good lo mein is the sauce. My sauce is easy and tasty natch. You can change the veggies to suit your taste (I add bok choy if I have it. You might like mushrooms, etc.) and you could even use a wheat based thin spaghetti instead of lo mein noodles if you wanted. (Lo mein noodles are made from wheat flour and eggs.) None of that matters. What matters is the sauce.
While veggies and beef are cooking, mix the following ingredients in a bowl: 1/2 cup beef broth; 1/4 cup soy sauce; 1/2 teaspoon white pepper; and one teaspoon sugar. Mix one and 1/2 teaspoon corn starch with one tablespoon water and then, add this to the broth-soy sauce mixture.
Cook lo mein according to package directions and add the cooked noodles to the wok. Pour sauce over everything and use tongs to coat everything evenly. Heat through, so sauce clings to noodles.
I like this spicier than my family, so I use rooster sauce (srirachi sauce) on mine. We also add hoisin sauce to the final dish when we have it on hand.
*You can add 1/4 teaspoon ginger to the sauce if you don't have any ginger root.