Every salad dressing needs some sugar. It adds sweetness, yes, but it also curbs bitterness and tames acidity, marrying your various ingredients to create one cohesive flavour profile. Maple, honey, and agave are all good additions, but they bring their own flavours, in addition to pure sweetness.
If you want to add that hit of sweet without muddying your salad dressing vision with other, incidental flavours, plain ol’ cane sugar is your best option. The granulated stuff can work fine but, depending on the temperature of your other ingredients, it can settle — undissolved — at the bottom of your dressing vessel. To help your sugar mix and mingle with ease, consider borrowing a trick from the cocktail world and reach for the simple syrup.
Dissolve white sugar in an equal amount of hot water (you can use the microwave), let cool, then add a teaspoon to your dressing. The syrup will disperse evenly and quickly with a shake, giving you a perfectly-balanced salad serum.