Wash the string beans and cut into 2 to 2 ½ inches long. Remove the top of the string beans. The easiest way is to take about 6 string beans, line them up and cut the top all at the same time. Then continue cutting into 2 to 2 ½ inches long. Set aside.
In a large skillet heat oil over medium heat.
Saute onion until translucent.
Add garlic and cook until golden.
Add soy sauce and pork.
Once pork turns pale in color, add the sitaw (string beans). Cover skillet until sitaw is half cooked.
Pour vinegar and add ground pepper. Note: Do not cover or stir until it boils for about 3 minutes.
Pour water bring to a boil.
Lower heat between medium to low, cover and simmer until vegetables are tender but crisp.
Salt to taste.
Notes
If you prefer a more sour dish, add more vinegar.
If you like more sauce, increase the ratio of vinegar and water accordingly.
Any adobo is best a day old, you can make extra servings and it keeps well up to 4 days in the fridge.