SubgumThere are so many variations on sub gum or subgum chow mein that I hesitate to post a recipe. You'll find it with brown sauce or with a light sherrry-laced sauce built around chicken broth. It essentially means with assorted vegetables, typically peppers, water chestnuts, mushrooms, snow peas, etc. (The word comes from the Cantonese "shap kam", meaning mixture.)
That said, when I was a boy in Chicago and most Chinese food was inexpensive takeout limited to a small handful of options, the style most seen there was very Americanized and included peas and cubed carrots, along with the inevitable celery in a light sauce.
Because of the stylistic differences, I suggest Chowderhead might want to pop the terms subgum+recipes into Google. You'll get hundreds of hits.
A recipe for Gai Kow Sub Gum marinates a cubed chicken breast in a bit of salted sherry, then stir fries a sliced onion, adding the chicken and liquid, stir-frying until chicken is white. Then 1/2 cup bamboo shoots, 1/4 cup sliced water chestnuts, 1/2 cup celery, 1 cup sliced mushrooms, and 1 cup frozen peas are added to the wok and stir-fried for 3 minutes. To this is added a 3/4 cup chicken broth mixed with 1 tbsp corn starch, stirring until thickened. Adjust seasoning, sprinkle with toasted almonds, and serve with pan-fried noodles.
Except for the missing carrots, that's close to the old Chicago style.