Pack a small saucepan with all aromatics and spices (suggested quantities above) EXCEPT the Pixian douban, and add just enough vegetable oil to barely cover (approx. 1½ cups). Turn heat to medium and bring the oil to a soft bubbling, then turn heat to low to let everything infuse slowly, until all the moisture has been cooked out of the fresh ingredients and the alliums are golden brown, 30-40 minutes. Add the ¼ cup of Pixian douban and cook for 5 more minutes, then turn off the heat.Let the oil cool. Pour everything into a non-reactive container, tamp and cover. Refrigerate to continue cold infusion for up to a week. When you’re ready to make candles, set a bowl in a pot of water to create a double boiler. Measure out 10 cups of soy wax (just short of 2 1/4 pounds) into the bowl and turn heat to high. While the wax is melting, set out candle jars and center the wicks using wick centering tools or strips of tape. Sieve the infused fragrance oil into a bowl.
When wax has completely melted, blend in 1½ teaspoons of red dye, 1 teaspoon orange dye and ½ teaspoon yellow dye. Adjust dyes as needed—the shade you are going for in the base layer is the red-orange of fresh chili oil. The color should look very saturated, since the color will become more pastel as the wax dries.
If you don’t have wick stickers, use a spoon to pour 1 spoonful of melted wax into the bottom of each candle over the wick, in order to affix the wick in place. Turn off the heat, then add 10 tablespoons of the fragrance oil to the wax—one for each cup of wax—and mix gently. Next, using a funnel and ladle, fill each candle jar about ⅔ full, dividing the wax evenly between all the jars. Try to minimize drips on the sides of the jar. Let the base layer harden, about 1 hour.
As the base layer hardens, melt another 5 cups of wax in the double boiler. When wax is fully melted, add 1 teaspoon yellow dye and ⅛ teaspoon orange dye and mix. This time, the shade you are aiming for is the deep marigold of congealed fat tinted by chili oil. When you are happy with the color, turn off the heat and stir in 5 tablespoons of fragrance oil.
Use the funnel and ladle to pour the yellow wax over the hardened red wax in the jars, leaving at least 1 cm of space at the top for decoration. Reserve a small amount of melted wax to correct any blemishes at the end.
Let the wax harden for 30-50 minutes, checking every 10 minutes. When wax is solid but still a little soft, trim the wicks so that they are flush with the top of the candle jar. Select nice-looking whole spices like chilies, star anise, coriander and Sichuan peppercorns and embed them in the surface of the candle. Leave space around the wick, as you don’t actually want the spices to burn. The surface may crack or buckle as you push the spices in. This can be fixed by spooning a little more of the reserved melted wax on top (though not directly on top of large spices) to re-smooth the surface. When the wax is hard, buff off any candle drips with a paper towel dipped in vinegar. Add candle labels, cover candles with their lids, and let them sit for 3 days to cure before lighting.