Preheat oven to 350°F (177°C). Grease an 8.5×4.5-inch loaf pan with butter or nonstick spray.

In a medium bowl, whisk the oil, honey, egg, yogurt, and vanilla together until combined.

In a large bowl, whisk the flour, baking powder, baking soda, salt, and cinnamon together. Pour the wet ingredients into the dry ingredients and whisk to combine. Avoid overmixing. The batter is thick. Fold in the zucchini, orange zest, and add-ins (if using).

Spread the batter evenly into the prepared pan. Sprinkle lightly with coarse sugar, if desired, before baking.

Bake the bread for 50–55 minutes, tenting loosely with foil about halfway through to prevent the top from over-browning. Poke the center of the bread with a toothpick. If it comes out clean, the bread is done.

Remove from the oven and allow the bread to cool in the pan set on a cooling rack for 1 hour. After that, remove the bread from the pan and let it finish cooling directly on the rack.

Slice and serve. Cover and store leftover bread at room temperature for up to 4 days or in the refrigerator for up to 1 week.