For the Marinade: In a large bowl, combine lamb pieces, Tikka Masala, salt and yogurt together, mixing well. Transfer to a large resealable bag, squeezing out the excess air and seal. Put the bag in a container (in case it leaks) in your refrigerator for at least an hour. Give it a 'squish' every once in a while to make sure that every piece of the lamb is coated.
If you're going to grill the lamb, get your barbecue grill set up and ready to go. You can also pan-sear these, or use a grill pan to cook the lamb.
For the Sauce: Heat the olive oil in a large sauté pan over medium heat. When the oil is hot, add the chopped onion and sauté until slightly brown. Then add the garlic, ginger, and salt. Stir occasionally, cooking until the onions are cooked through. Now add the Aleppo Pepper and Tikka Masala, stirring several times to thoroughly mix in. Mix in the canned tomatoes and cook, stirring occasionally, until the mixture has reduced slightly and the color has deepened. (This should take about 15 minutes.) Add the coconut milk, thoroughly mixing it in, and reduce heat to low. This will let the sauce thicken while you're cooking the lamb skewers.
While the sauce is reducing, take the bag of marinated lamb out of the refrigerator and put the lamb onto a plate. Thread the lamb onto your skewers (leave as much of the yogurt mixture on the lamb as possible - that's "flavor"). Grill (or saute) the lamb until the meat is browned and cooked to your desired doneness.
Garnish with mint or cilantro leaves before serving.