Blanch the oysters in boiling water for 1 minute, then remove and drain on paper towel.
Heat a wok until just smoking. Add the peanut oil and, when hot, stir-fry the black beans, garlic, ginger, chilli and capsicum until fragrant. Add the spring onions, soy sauce and sesame oil and stir-fry for another minute, then add the oysters and toss to heat through. Sprinkle with coriander to serve.