* For colorful appeal, I often use two zucchini and one summer squash.
When simmering the balsamic syrup, err on the side of thinner than you think, as the mixture will thicken slightly upon cooling, and you can always put it back on the stove or simply enjoy a thinner syrup. If you reduce it too much, it will become too sticky to drizzle.
Helpful hints: A very gentle simmer over medium-low heat (or whatever heat will achieve this on your stove) minimizes vinegar fumes and possible scorching of the pan. To easily clean your pan if it becomes scorched (the vinegar mixture can leave a burned residue around the edges, although this is a good anytime tip), cover the affected areas with a paste of baking soda and water and let sit for an hour or more. If the residue doesn’t scrub off easily at this point, scrub with a crumpled piece of aluminum foil, adding a bit more baking soda, which acts as a gentle abrasive, as needed. (For nonstick or ceramic pots, use a scrubber that is appropriate for those pans, as the crumpled foil will scratch them.)