In a large skillet, over medium high heat, add the vegetable or corn oil.
Add the garlic, onions and celery. Sautee these quickly for 1 to 2 minutes till onions become translucent.
Add the pork slivers. (If desired, add the sliced chicken and shrimps at this time). When meat turns from pink to a brown color after about 8 minutes, add the broth and fish sauce.
Blend well and add the soy sauce. Mix in the carrots. Cook for 1 to 2 minutes to soften. Then add the green beans, which will take 6 minutes to cook.
Add the shredded cabbage, which will take 1 to 2 minutes to cook. Do not overcook cabbage or it will get too transparent and disappear in the dish.
At this point, broth should be very hot and blended well with the flavors of the meat and vegetables. Slowly add in the noodles in two or three batches. Coat the noodles with the sautéed vegetables-meat-broth mixture. Keep turning the ingredients around the skillet till the noodles turn from a fair white color to a golden hue from the sauce.
Season with salt and pepper. Pour in the drops of sesame oil.
Garnish with scallions. Sprinkle the lemon juice over it. Serve hot.