Put the onion into the food processor and process until finely chopped. Gather the onions to one side of the work bowl and use a paper towel or a clean kitchen towel to press as much liquid out as you can.
Add the meat, salt, spices, and baking powder (baking soda for AIP), and process for about 30 seconds to one minute. You want the meat to be smooth and well-blended. This might seem weird, but it works!
Form the meat into kebabs. It will be sticky, and if you want you can dip your fingers into a bowl of cold water between kebabs to make them less sticky. You can either put them on kebab skewers, or just form them into a long sausage shape and place them on a baking sheet. If you have more than you need, or are cooking ahead, you can put them on an extra baking sheet to flash freeze.
Cook them under the broiler under full heat. This will be very quick, about 5 minutes on each side. You'll know they're done when they start to brown a bit and smell ridiculously good. For the ones you have frozen, bake straight from the freezer at 450 F (230 C) for 8-10 minutes on each side.
Garnish the Chelo Beef Kebabs with fresh herbs and lemon wedges. This is delicious served with a cucumber yogurt mixture (you can use coconut yogurt) and cauliflower rice.