In a medium bowl, whisk together the mayonnaise, olive oil, lemon juice, garlic, Dijon mustard, anchovy paste, Worcestershire sauce, sugar, and finely grated Parmesan.
If you used 1 teaspoon of vinegar for the onions, start by adding the remaining teaspoon to the dressing, or simply adjust to taste. You can also use fresh vinegar for the dressing if you prefer a more pronounced tang.
Season with sea salt and freshly ground black pepper.
Whisk until smooth and creamy. Taste and adjust the lemon, vinegar, sugar, or seasonings as desired.
Refrigerate until ready to assemble.