In a large bowl, combine the ground beef and ground pork.
Add the minced garlic, chopped onion, baking soda, paprika, black pepper, and salt.
Pour in the sparkling water (or cold water) and mix everything thoroughly until well combined. The mixture should be slightly sticky.
Wet your hands to prevent sticking. Take small portions of the meat mixture and shape them into small, finger-sized sausages, about 4 inches long and 1/2 inch thick.
Preheat your grill to medium-high heat.
Place the Ćevapi on the grill and cook for about 3-4 minutes per side, or until they are well-browned and cooked through.
Serve the ćevapi in flatbreads or pita bread with sliced onions and ajvar. Optionally, add a dollop of yogurt or sour cream on the side.
Enjoy your meal!