This is the closest I can get to the best tartar sauce I've ever eaten, at a restaurant in Galveston, TX. I don't remember the name of the restaurant, but I've been trying to copy the recipe, and I think it is just right now. It will keep about a week in the refrigerator if you rinse the sliced onions in hot water before chopping or grinding them. This will keep the sauce from turning yellow. This is great with fried fish or shrimp.
- Mix together mayonnaise, mustard, pepper, salt, and pickle relish.
- Grind together onions, parsley, and capers. You can use a hand blender or a food processor.
- Add to the mayonnaise mixture and mix well. Refrigerate until ready to use.