In a large mixing bowl, combine the ground beef, finely chopped red onion, minced garlic, green chillies, cilantro, dill, parsley, nutmeg, allspice, salt, pepper, and ground rice flour. Mix everything together until just combined, being careful not to overwork the meat.
Using your hands, form the mixture into small meatballs, about 1 to 1.5 inches in diameter. Place them on a plate or a baking sheet as you go. This should yield around 20-25 meatballs, depending on the size you choose.
In a large skillet, heat 1 teaspoon of olive oil over medium heat. Once hot, add the meatballs in batches, being careful not to overcrowd the pan. Cook for about 4-5 minutes on each side until they are nicely browned. Remove the meatballs from the skillet and set them aside.
In the same skillet, add the minced onion and garlic. Sauté until the onion is translucent and fragrant, about 3-4 minutes. If you’re using green chillies, add them now and cook for an additional minute.
Pour in the canned crushed tomatoes, then add the bay leaves, nutmeg, salt, and pepper. Stir well to combine. Allow the sauce to simmer for about 5 minutes.
Return the meatballs to the skillet, nestling them into the sauce. Reduce the heat to low, cover, and let them simmer for another 15-20 minutes. This will ensure the meatballs are cooked through while soaking up all the delicious flavors of the sauce.
While the meatballs are simmering, prepare the yogurt sauce. In a small bowl, whisk together the cold plain yogurt and cornstarch until smooth. Stir in the fresh cilantro, parsley, and dill. This cooling sauce will balance the heat of the meatballs perfectly.