Add the onion, garlic, ginger, and Serrano pepper to a food processor or blender, and blend until smooth, scraping down the sides a few times if needed.
Add the ground meat to the food processor and blend until minced/smooth and well combined with the onion mixture. Pour this into a bowl, along with the spices and tapioca flour.
Form the meat mixture into 1-inch balls, and set aside in the fridge to firm up for now.
To make the curry, heat oil in a dutch oven or heavy pot over medium heat, then add cumin seeds. Once they begin to splutter, add the cinnamon stick and bay leaves. Stir briefly, then add the onions and cook for 10 minutes, or until they begin to brown.
Add the garlic, ginger, Serrano pepper and cook for 1 minute, then add the tomato sauce and spices to the pan and cook for 5-6 minutes, stirring frequently.
Add the water, mix well, then add koftas. Cover with a lid, reduce the heat to medium low, and cook for 12-15 minutes or until the koftas are cooked through.
Remove lid, raise heat to high and cook for 5 minutes.
Garnish with cilantro and serve.