This riff on Chinese zha jiang mian—or noodles with pork and fermented bean sauce—substitutes prepared black bean garlic sauce for the traditional and harder-to-find fermented yellow or brown bean paste. On its own, the sauce tastes intense, but its boldness is balanced by the neutral flavor of the noodles and the freshness of the cucumber. You can find it in the Asian aisle of most larger grocery stores. Make sure to thoroughly drain the noodles before portioning them; excess water clinging to them will dilute the sauce.