To prepare frozen kebbe or shish barak, Heat oven to 200 C (400 F). Lighly oil a baking sheet then place frozen kebbe or shish barak onto the baking sheet, no need to defrost. Drizzle with additional oil and toss to combine. Bake 20-30 minutes until golden brown, turning over halfway through.
For the Yogurt Sauce:
Heat a small skillet over medium high heat, and saute the chopped coriander and crushed garlic with a pinch of salt until the garlic has just turned golden. Set aside.
Mix the amount of cornstarch you will be using (1 heaped tbsp for a thinner sauce, 2 for a thicker) with just enough cold water to form a paste.
Using a blender or immersion blender, blend together the yogurt, the egg, the cornstarch paste,and the salt until well combined.
Pour yogurt mixture into a heavy saucepan over medium heat and immediately start whisking. Keep whisking and don't stop or the sauce will separate. After around 10 minutes or so, the sauce will begin to boil and as soon as that happens take it off the stove.
Add the fried garlic and coriander mix, stir and taste for seasoning. Add the yogurt drink if desired and especially if sauce is too thick.
If using this yogurt sauce for the cooked kebbe and shish barak, add them right before serving so they retain their crunch. Garnish with fresh coriander and toasted pine nuts.
Serve with vermicelli rice and enjoy!