Sprinkle the chicken legs on all sides with salt, add to a large bowl or Ziploc bag. Stir together the soy sauce, vinegar, beer, cornstarch, brown sugar, garlic, and ginger until well combined.
Pour over the chicken. Cover (or seal) and refrigerate for 3 to 24 hours.
Preheat the grill to medium-high.
Cover a baking sheet with aluminum foil, place the chicken on the prepared sheet pan.
Pour the marinade into a pot, boil until thickened, about 9 minutes.
Add the chicken to the grill. Once the chicken is on the grill, remove and discard the aluminum foil leaving the sheet pan to be a clean place to put your chicken once it’s cooked. Do not put cooked chicken back on a plate or pan that once held raw chicken or you will risk bacteria contamination.
Brush the chicken with glaze every time you turn the chicken. Allow the chicken to cook until the juices run clear and chicken is cooked through. If the chicken starts to burn before cooked through, lower grill temp or move chicken to the upper rack of the grill.
Sprinkle with chopped chives or green onions.