How to Make It
Preheat the oven to 400°. In a skillet, toast the cumin, black peppercorns, Sichuan peppercorns, dried chiles, fennel seeds and star anise over moderate heat, stirring, until fragrant, 3 minutes. Let cool, then finely grind. Transfer to a bowl and mix with the onion and garlic powders and ginger.
Set 2 racks over each of 2 rimmed baking sheets. Lightly brush the lamb all over with oil and then soy sauce. Rub the spice mixture all over. In a skillet, heat the 2 tablespoons of oil. In batches, sear the racks over moderate heat until browned on both sides, 2 minutes per batch. Transfer to the baking sheets.
Roast the lamb for 45 minutes, until an instant-read thermometer inserted in the center registers 135°. Let rest for 15 minutes.
In a saucepan, combine the veal stock, ginger, garlic, tobanjan, cinnamon, sugar, cloves, cardamom, Sichuan peppercorns, dried chile, star anise and fennel seeds. Simmer over moderate heat until reduced to 1 cup, 15 minutes. Whisk in the butter and season with salt; strain into a bowl and keep warm.
Carve the lamb into chops and drizzle with the sauce. Garnish with scallions, sliced red chiles and crispy shallots and serve.
Tobanjan (spicy, fermented broad-bean paste, also sold as doubanjiang) and Chinese dark soy sauce are available in Asian food stores. For crispy fried shallots, very thinly slice them crosswise into rings and dust with Wondra flour; fry in 1 1/2 inches of 325° vegetable oil until golden and crisp, then transfer to paper towels to drain.