Transfer the chicken legs to a large sous vide bag in one layer and seal using a vacuum sealer or a hand pump. Reserve the marinade in a small bowl and set aside.
Once the water is ready, slowly lower the chicken into the prepared water bath. Make sure the chicken drumsticks are completely under the water. Cook chicken for 2 hours.
Optional: Once the chicken is done, remove the bag from the water bath and drop it into an ice bath to fully chill. This step will help get extra-crispy skin when you sear it without overcooking the chicken underneath.
Remove the chicken from the sous vide bag and scrape off any gelled juices using your fingers. Reserve the juices for other uses.
Pat the chicken with paper towels. Heat a nonstick pan or cast iron skillet over high heat on the stove until hot. Place chicken in the skillet and sear for 1 minute on each side or until the skin is golden brown and crispy. Transfer the chicken to a plate and let it rest.
While the chicken is resting, add the reserved marinade to the same skillet, bring to a rapid boil and continue cooking until the sauce is reduced and thickened, about 2-3 minutes. Pour the honey balsamic sauce over the chicken legs and enjoy!
When making the honey balsamic sauce, if the sauce is too thick, add some reserved chicken juices to it. If your sauce is not thick enough to your liking once you reduce it by half, dissolve 1 teaspoon cornstarch in 1 tablespoon cold water and stir into the sauce. Keep stirring, and the sauce will thicken nicely.
Marinating the chicken overnight will enhance the flavor even more.