Yield: 2 cups

Method:

Line a large pot that is at least 4 inches deep with 2 layers of aluminum foil. Place the wood chips in the pot. Put a round wire rack over the chips. (There should be some space between the surface of the rack and the chips.) Place the rhubarb on the rack, spreading it out evenly, and cover the pot tightly with more aluminum foil. Warm the pot over medium heat until you can smell smoke from the chips. Turn the heat to low and smoke for 15 minutes. Remove the pot from the heat and pull back the foil covering in a well-ventilated area. Remove the rhubarb and roughly chop. Set aside.

In a small pot, heat the canola oil over medium-high heat until shimmering. Add the onions and cook until translucent, about 2 minutes. Add the rhubarb, orange juice, brown sugar, Worcestershire sauce, and rosemary. Bring to a simmer over medium heat, stirring often, until the rhubarb has broken down and the sauce has reduced by half, approximately 15 minutes. Remove from the heat and let cool to room temperature.

Transfer the contents of the pot to a blender and purée until smooth. Strain the sauce through a fine-mesh sieve. Use immediately or refrigerate.