Stir-Fried Green Beans in Black Bean-Tofu Sauce

The addition of hot chillies - preferably serrano - and fermented chilli paste with fermented black beans, transforms this simple green bean stir-fry into an unusual fiery dish. Serve immediately or let cool to room temperature. Steamed rice is a good bland counter-point, and another stir-fry such as asparagus and mushrooms, or whole steamed fish with sizzling hot chilli oil, would also be a delicious accompaniment.