Filipino minced beef with string beans (ginisang baguio beans)

I first learned this recipe many years ago from a college friend. I misplaced her recipe, so we tried this one: http://www.russianfilipinokitchen.com/2014/07/30/sauteed-green-beans-with-ground-beef-filipino-style-ginisang-baguio-beans/ Our modifications: consistent with my friend’s recipe, we used ¼ cup white vinegar instead of water. We added the vinegar at the same time as the soy sauce, salt, and black pepper. Second, we often have reduced the string beans to 12 oz (¾ lb) and sometimes supplement with 1/3 block of five-spice pressed tofu cut into matchsticks. Third, we have sometimes used ¼ tsp white pepper instead of black pepper. We sometimes substitute minced chicken for beef. (May 2020)