Trim all visible fat from the meat and cut it into 36 cubes of roughly 2-inches.
In a large bowl or measuring cup, place all the ingredients for the marinade and stir until well combined. Place your meat in a non-reactive container and pour the marinade over it. Massage it into the meat with your fingers, making sure that all the pieces are well coated. Arrange the meat in a single layer, cover with plastic film and refrigerate for at least 4 hours, or preferably overnight.
Make the tahini sauce: combine all the ingredients together in a mixing bowl and stir until smooth and creamy. Keep refrigerated until ready to serve.
When you are ready to eat, lightly oil the grate of your outdoor grill and preheat it to very high heat (550°F - 600°F)
While the grill is heating, thread the lamb meat onto skewers, placing 1 fresh mint leaf between each piece of meat.
Place the kabobs on the hot grill, lower the heat to medium-high, close the lid and let the skewers cook for about 2-3 minutes then flip them over and continue cooking for another 2 to 3 minutes for medium rare.
Remove the kabobs from the grill, cover loosely with foil and let them rest for 2 minutes before serving.