Preheat your oven to 400°F. In a bowl, combine the salt, pepper, chili powder, cumin, and garlic powder. Rub the lamb with the spices on all sides.
Place a pan over medium-high heat. Sear each side of the lamb. Put the seared lamb on a baking sheet.
In a bowl, combine the brown sugar, honey, rice vinegar, hoisin sauce, and soy sauce. Brush the seared lamb with the sauce. Bake for 20-25 minutes. You want the lamb to be 135°F for it to be medium rare.