Step 1

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.

Step 2

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.

Step 3

Roast the lamb for 45 minutes, until an instant-read thermometer inserted in the center registers 135°. Let rest for 15 minutes.

Step 4

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.

Step 5

Carve the lamb into chops and drizzle with the sauce. Garnish with scallions, sliced red chiles and crispy shallots and serve.