How to Make It
Combine 1 quart lukewarm water, 1/2 cup salt, and honey in a large pot. Juice the orange, and add the orange juice and rinds to the pot. Bring to a boil over high, stirring to dissolve the salt and honey. Remove from heat, and add the tea; steep 10 minutes. Pour the brine through a fine wire-mesh strainer into a nonreactive container large enough to hold the pork (I use an oval 6-quart enameled Dutch oven); discard the solids. Add 1 quart ice water, and stir to cool completely. Submerge the pork in the brine, and refrigerate at least 12 hours or up to 24 hours.
Remove the pork from the brine, and pat dry; discard the brine. Place the pork, fat side up, on a large rimmed baking sheet. Season with 1/2 teaspoon black pepper. Place the pan in the center of the oven, and preheat to 250°F. (Slowly warming the roast in the oven as it preheats eliminates the need to bring the roast to room temperature first.) Roast 1 hour.
Meanwhile, in a small heavy saucepan, combine the plum jam, orange juice, vinegar, crushed red pepper, and 1/4 teaspoon salt. Bring to a simmer over medium-high. Simmer, stirring occasionally, until reduced by about two-thirds to a thick, jammy glaze, 8 to 10 minutes. Set aside to let cool slightly.
After pork has roasted 1 hour, coat all sides of the pork with the glaze. Continue roasting at 250°F, fat side up, until an instant-read thermometer inserted in thickest part of roast reads 135°F, about 2 hours. Transfer the pork to a cutting board to rest for 20 to 30 minutes.
While the pork rests, increase the oven temperature to 475°F. Pile the fennel in the center of the baking sheet, drizzle with the olive oil, and season with 1/2 teaspoon salt and remaining 1/4 teaspoon black pepper. Toss to coat, scraping up the pork drippings from the pan and mixing them in. Spread the fennel in an even layer. Place the pan in the oven as it is coming up to temperature, and roast the fennel until tender and browned in spots, about 20 minutes.
Season the plums with the remaining 1/4 teaspoon salt. Add them to the pan and toss to combine with the fennel. Clear a space for the roast and return it to the center of the pan, fat side up. Roast at 475°F until the glaze is caramelized and bubbly, the plums are tender and just barely hold their shape, and the fennel is meltingly tender, 10 to 12 minutes.
Let stand for 5 to 10 minutes. Transfer the pork to a cutting board, and carve between the ribs into 6 chops. Scatter the basil over the fennel and plums, and toss to combine; serve warm or at room temperature.