1. Preheat oven to 350 degrees. Using a vegetable peeler, peel oranges, yielding 8 to 10 broad strips from each fruit. Using a paring knife, scrape white pith from inside the peels.

2. Place the peels in a small saucepan with 1 cup water and sugar. Set over high heat, and bring to a boil. Reduce heat to medium, and simmer until the liquid becomes syrupy, 10 to 15 minutes. Remove peels, and drain.

3. Line a baking sheet with aluminum foil, and spread with oil. Scatter the cooked peels on the foil, spaced so they aren't touching.

4. Bake peels until dry, being careful to avoid any browning, about 15 minutes. If they begin to brown, reduce oven temperature. Transfer to a wire rack to cool at room temperature in a dry place.

5. Crumble peels, then grind in a spice mill or coffee grinder until powdery. Store in an airtight container. Orange dust will retain its peak flavor up to 2 weeks, but it will keep virtually forever, gradually losing its intensity.