Wash and pat dry the beans. Snap the ends off of the beans.
Mix together black bean sauce, garlic sauce, pepper, soy sauce and sugar and set aside.
Heat oil in a large frying pan or wok. Once hot, add beans in a single layer. May have to do multiple batches. time. Don't over-crowd the pan.
Cook until they are begin to shrivel and turn brown in places. Transfer to a paper towel and sprinkle with salt and cook your next batch.
The beans should still be crisp at this point, not mushy.
Put all the beans back into the pan and then add the garlic and cook until the garlic is fragrant. Add the sauce. Stir-fry for about 3-4 minutes. Drizzle with sesame oil.