Ingredients
Method
- Grate the onion on the small holes of a box grater until you have about 1 tablespoon of pulp. Pile it into a paper towel, gather the corners, and squeeze over the sink until the liquid stops running.
- Put the mayonnaise in a medium bowl. Add the ketchup, dill relish, mustard, squeezed onion, pickle brine, Worcestershire, garlic powder, smoked paprika, and black pepper.
- Whisk until the sauce is smooth and one even color, with no ketchup streaks running through it. About 30 seconds.
- Taste and add salt if needed. Adjust from here: more ketchup for sweetness, more brine or mustard for tang, more smoked paprika for depth.
- Cover and refrigerate at least 30 minutes before serving so the flavors settle. It's good right away, but better after a rest.
Notes
The ratio is 8-3-2-1 in tablespoons: 8 mayo, 3 ketchup, 2 dill relish, 1 yellow mustard. Everything else is seasoning at roughly 1/2 to 1 teaspoon per 1/2 cup of mayo. Scale it from there.
Squeeze the grated onion until it is genuinely dry. Onion is mostly water, and that water thins the mayo into a runny sauce that slides off the bun.
Fresh grated onion is best for sauce you'll eat within a few days. Raw onion keeps developing sulfur compounds in the fridge, so it turns sharper by day three or four. For a make-ahead batch meant to keep a week or more, swap in 1/2 teaspoon onion powder instead.
If it tastes flat, add ketchup or pickle brine rather than more mayo. Mayo mutes flavor.
Makes about 3/4 cup, enough for roughly 6 burgers at 2 tablespoons each.
Don't freeze it. Mayonnaise-based sauces separate and turn grainy when thawed.