Place the onions in a blender or food processor and process to puree. Strain through a fine-mesh sieve into a 2-cup measuring pitcher, pressing firmly with a rubber spatula or the back of a wooden spoon to extract all the juice. Discard the solids. Add the lemon juice and enough water to measure 1 1/2 cups liquid. In a large bowl, combine the onion juice mixture and the bulgur and soak for 10 minutes. Add the beef, pine nuts, garlic, 1 teaspoon of the salt, the cumin, cinnamon, cardamom and pepper to the bulgur and stir to mix well.
Using a little less than 1/3 cup for each kebab, form the beef mixture into 16 sausage links, each about 4 inches long and 3/4 inch in diameter. Thread onto the skewers. If the mixture is too crumbly, add water 1 tablespoon at a time, just until it holds together. Cover the prepared skewers and refrigerate until ready to cook.
Prepare a hot fire in a charcoal grill or heat a gas grill or broiler (grill). Away from the heat source, lightly coat the grill rack or broiler pan with cooking spray. Position the cooking rack 4 to 6 inches from the heat source.
In a small bowl, whisk together the yogurt, tahini, lemon zest, mustard and the remaining 1 teaspoon salt. Cover and refrigerate.
Place the kebabs on the grill rack or broiler pan. Grill or broil the kebabs, turning as needed, until evenly browned, about 8 minutes. Drizzle with the yogurt sauce and garnish with the cilantro.