Process the onion with 2 tbsp of water in a food processor to a paste or grate it on a grater. In a large bowl combine both meats, onion, egg, spices and chopped fresh cilantro, oats, salt and pepper.
Form meatballs approximately the size of golf balls. Use a small ice cream scoop to get even sized meatballs. Arrange them on a cutting board and put them in the freezer for 10-15 min to firm up.
Brown meatballs in batches over medium high heat on all sides in hot oil, they don't need to be cooked all the way through. Remove to a paper towel lined plate. Discard the oil meatballs were browned in and wipe the pan with a paper towel.
To the same pan add pomegranate molasses, beef or chicken stock, brown sugar and spices. Bring to a boil and simmer until it starts to get thicker, add a mixture of corn starch and water and stir with a whisk to make sure there are not lumps. Add half of the pomegranate seeds to the sauce together with meatballs.
Simmer for 15-20 minutes shaking the pan once in a while to prevent meatballs sticking until the sauce is thick and syrupy. If your sauce is still thin after the time stated continue simmering until it has the consistency of glaze.
Serve sprinkled with the remaining pomegranate seeds and chopped fresh mint leaves.