Place the tamarind in a large saucepan and pour in enough water to cover by 1 inch. Cook over medium-low heat, covered, until soft, about 30 minutes. Mash and then push through a strainer, discarding the seeds and strings. Reserve the pulp.
Melt the butter in a saucepan over medium-high heat. Saute the shallots with the salt and ground pepper until golden brown. Add the garlic and cook 2 minutes longer. Add the chicken stock and tamarind pulp. Bring to a boil, reduce to a simmer and cook 10 minutes. Stir in the Worcestershire, cayenne and honey. Remove from the heat and keep warm.
Preheat the oven to 350 degrees. Mix together the celery seed, cracked pepper, sesame and cumin in a small shallow bowl. Season the chops all over with salt. Firmly press each into the seed mixture to coat all over. Set aside.
In a large, cast-iron skillet that comfortably holds all 8 chops, heat the oil to very hot but not smoking. Cook the chops in the bubbling oil until the seeds are golden, about 2 minutes per side (do not worry about a few seeds slipping off). Transfer to a baking dish and bake 2 minutes for medium rare. To serve, coat each of 4 plates with the tamarind sauce. Top with 2 lamb chops each and serve.