In a small bowl, combine vinegar, lemon zest, lemon juice, shallot, and garlic, and let sit for 15 minutes. Add dill, mayonnaise, sugar, salt, and pepper, and whisk to combine. Gradually add olive oil to vinegar mixture, whisking constantly, until all is combined and mixture is smooth. Cover, and refrigerate for at least 2 hours, or up to 3 days.