You may tenderize the meat with Meat tenderizer, meat tenderizer powder, or baking soda. The BEST way that I recently tested is to add some coconut milk and marinate for overnight. You can use any kinds of your favorite marinate sauce. This is what I like and homemade easy!
Adapted from aohmc.blogspot.com
Combine all ingredients together and storage in a covered container. Refrigerate and marinate at least over night. Grill them on a outdoor or indoor grill pan next day.