This is a very popular dish in Thailand.  You can add tofu, beef, chicken or pork to the recipe as per the directions below.

If you are adding tofu:  Crumble 12 oz. firm tofu and drizzle with 1 T. soy sauce and 1 t. sesame oil.  Stir fry in 2 T. cooking oil until browned.  Set aside.

If you are adding meat:  Stir fry 12 oz. ground or minced chicken, beef or pork until fully cooked and nicely browned.  Set aside.

Thinly slice 1 onion.  Remove the core and seeds from 2-4 sweet peppers and thinly slice make 3 C. loosely packed.  Remove the leaves from a bunch of basil until you have 1 C.  Leave them whole or tear into large pieces.  Mince 2-3 cloves of garlic.
Trim the ends from 1/2 lb. of green beans. Cut into 2 inch pieces.

Optional:  Fine chop 1-4 Thai chiles or other hot peppers of your choice.

Heat 2 T. cooking oil in a wok and add the onions.  Stir fry until soft.  Add the peppers and continue cooking until the onions begin to brown.  Add the green beans along with the chiles and garlic and cook until they are tender.  (If using meat or tofu, add now).

Add the basil and 2 T. oyster sauce.  Stir fry for another two minutes, until everything is coated and the basil has wilted.  Serve over rice.