Prepare all ingredients (mise en place)- make sure all chopping is done and ingredients are laid out.
Add sesame oil to the wok and get it smoking hot.
Once the oil is smoking hot, add pork and chile pepper and cook 5-6 minutes, or until no longer pink, stirring constantly.
Add garlic and stir for 30 seconds; then add oyster sauce and stir occasionally for a couple of minutes until it thickens a bit.
Add celery and stir in for about 1 minute; then add chard, fish sauce, vinegar and sherry and cook for about 2 minutes, or until chard leaves are wilted.