In a bowl, combine all the ingredients listed above. Make sure the onion is strained through a cheesecloth to remove as much moisture as you can.
Add your softened butter and mix the meat, pressing your hands into fists to really knead the meat. The meat is ready when it doesn’t stick to your hands and you can see the web of fat stretch and run through the beef. Let it sit for at least 30 mins.
To shape the kebabs, take a golf ball sized piece and round it out between your palms. Press onto the skewer from the side and with your fingers, apply gently pressure to shape the kebabs in a thin log down the skewer. Make indentation marks on its surface by using your thumb and forefinger.
Bake in a preheated oven at 450 F for 14-18 minutes, flipping half-way through. I like to turn on the broiler for the last 3-5 mins to give a deeper color to the kebabs. If you have an outdoor grill, use that!
Slide the kebabs off the skewer using tongs while hot, and serve with naan, salad and mint raita.