In a spice or coffee grinder coarsely grind cumin seeds, peppercorns, caraway seeds, red pepper flakes, sugar and salt until only a few whole spices remain. This will be a coarse spice rub.

Clean and heat grill to 425°F, indirect heat (for a charcoal grill, bank coals on one side of grill; for a gas grill, leave one or two burners off on one side).

In a bowl or plastic bag add cubed lamb and spice rub. Massage lamb, pressing spice blend onto the meat with your hands to coat.

Thread lamb cubes onto 8-12 skewers, leaving a small gap between each piece of meat. Drizzle with olive oil.

Grill lamb over direct heat, turning every minute or so, until browned and you see visible char marks, about 4 minutes. Move to cooler side of grill and continue to grill until lamb is cooked to desired doneness, about 4 minutes longer for medium-rare.