Let's work on the onion first. You need a grater for this. No ifs ands or buts! You're going to grate your onion. It's easiest to go side by side leaving the middle intact. Once you have grated the onion, you need to squeeze out the onion juice. I use a paper towel because I never have a cheesecloth handy (who just has that lying around?).
Use a few paper towels and squeeze out the juice from the grated onion.
Add your ground beef, lamb, garlic, onion, baharat, salt and pepper to a mixing bowl. I recommend putting gloves on and mixing with your hands. You are going to have to use your hands to shape the kebabs anyway.
If you are using wooden skewers, be sure to soak them.
Skewer your meat into your skewers being sure to squeeze the mixture to mold it to the skewer. You want to use your thumb and press down gently as you go.
Using a grill on medium high heat, Place the meat on and cook for 4 minutes. Flip over and cook for another 4 minutes. Check your internal temperatures to cook to your liking.