Add the mayonnaise, pickles, onion, lemon juice, pickle brine, fresh dill, Dijon mustard, Worcestershire sauce, salt, garlic powder, and black pepper to a medium jar or bowl.
Stir vigorously until well blended. Taste and add extra salt if needed. For reference, we did not add any extra to ours.
Cover and refrigerate for at least 30 minutes before serving to let the flavors develop. Stir well before each use.
Notes
Store in an airtight container in the refrigerator for up to 3–4 days. Give it a good stir before serving.
A jar with a tight-fitting lid works great for mixing and storing this tartar sauce.
Finely chop the pickles and onion so they blend evenly into the sauce.
If you don't have fresh dill, substitute ½ teaspoon dried dill weed.