Whisk together the first 6 ingredients, then taste and add black pepper as needed. Toss to coat the string beans.
Lay out in a single layer on an unlined baking sheet.* Bake for 20-25 minutes, broiling for 1-2 minutes at the end.
Let cool completely before storing in the fridge.
Notes
*If you line the baking sheet with parchment paper, then the liquids may not cook off as much in the oven. In that case, simply remove the string beans from the liquid once done cooking before putting away.
Recipe by Lenses and Lentils at https://lensesandlentils.com/chinese-baked-string-beans/