Serves: Makes three 8 ounce bottles of ketchup
- 2 tablespoons pulverized apple wood smoking chips
- 1 medium yellow onion, cut into ½-inch-thick rounds
- 1 (28-ounce) can crushed tomatoes, including the juice from the can
- 1 tablespoon capers, drained and rinsed
- ½ cup firmly packed light brown sugar
- Juice of 1 orange, strained
- Juice of ½ grapefruit, strained
- Juice of ½ lemon, strained
- ¼ cup cider vinegar
- 2½ teaspoons kosher or sea salt
- ¼ teaspoon freshly ground black pepper
Using a stovetop smoker or wok, place the wood chips in two small piles in the center of the pan. If using a smoker, place a drip tray, covered with aluminum foil, on top of the chips. If using a wok, set a large sheet of aluminum foil loosely in place over the wood chips. Place a wire rack on top of the drip tray or foil. Arrange the onion slices on the wire rack. Slide the lid on the stovetop smoker or cover the wok, leaving it slightly open, and then place the smoker over medium heat. When the first wisp of smoke appears, close the lid. Smoke the onions for 5 minutes, then turn off the heat and leave the onions in the smoker or wok, with the lid tightly closed, for an additional 5 minutes. Remove the onions from the smoker and coarsely chop.
Purée the tomatoes in a blender on high speed until liquefied, about 2 minutes. Transfer the tomatoes to a deep 6-quart saucepan or Dutch oven and reserve.
Purée the onions and capers in the blender on high speed for 1 minute. Add the sugar and continue blending on high speed until the onion mixture is smooth, about 1 minute longer. Add the citrus juices, vinegar, salt, and pepper and blend to incorporate. Transfer the onion mixture to the pot with the tomatoes and stir to combine.
Over medium heat, bring the tomato and onion mixture to a simmer. Decrease the heat to maintain a low simmer, and cook, stirring occasionally, until the sauce thickens to a ketchup consistency, 50 minutes to 1 hour.
While the ketchup is simmering, wash the bottles in hot, soapy water and dry thoroughly. Alternatively, run the bottles through the regular cycle of your dishwasher.
Using a funnel, ladle the ketchup into the prepared bottles, leaving ½-inch headspace. Wipe the rims clean and secure the lids. Label and refrigerate.
Storing: Refrigerate for up to 2 months.