Trim chicken feet of nails and any dark, callused areas. Scrub with rock salt, rinse, and drain well.
In a large pot, combine chicken feet, enough water to cover, ginger slices, and green onion stalks. Boil for about 7 to 10 minutes, skimming scum that floats on top. Remove from pot and pat dry.
In a deep pot or wok, heat about 3 inches oil. Carefully add chicken feet and cook for about 3 to 4 minutes or until lightly browned.
Remove from oil and soak in iced water for about 1 hour or until skin is wrinkled. Drain well.
In a large pan, heat about 1 tablespoon oil. Add onions and garlic and cook until softened.
Add chicken feet, vinegar, soy sauce, 1 cup water, peppercorns, bay leaves, and chili peppers. Boil uncovered and without stirring for about 2 to 3 minutes.
Lower heat, cover, and continue to cook for about 50 to 60 minutes or until chicken feet are tender and liquid is reduced. Add more water in ½ cup increments if the sauce is drying out before the meat is tender.
Add oyster sauce and season with salt to taste. Stir to combine and cook for another 1 to 2 minutes. Serve hot.