Mix yogurt, tandoori powder, lemon juice, oil, salt and pepper into a paste.
Cut the lamb into 1” cubes. Combine the lamb and marinade in a bowl, cover with plastic wrap, and put in the refrigerator for at least one hour, but over night if possible.
Heat grill to high. Thread the meat onto the skewers of your choice and grill, turning often. Cook to an internal temperature of 130° to 140° for medium-rare, or 140° to 150° for medium.
Serve with Naan Bread and Cucumber Raita (recipe below).
Tandoori Powder
Combine all the ingredients and keep in an airtight container.
Cucumber Raita
Grate the cucumber with the fine holes of a box grater. Put the pulp in a towel and twist tightly to squeeze out all the water.
Place the cucumber pulp in a bowl and add all the other ingredients. Mix until uniform.
Refrigerate overnight.