Preheat the oven to 390F (200C).
Heat the olive oil in a large non-stick skillet over a medium-high heat.
When hot, add the onions, garlic, and chili flakes, then season with salt and black pepper. Cook for a couple of minutes or until golden brown. Remove from the skillet and set aside.
In a mixing bowl, add the ground turkey, egg, almond flour, parmesan cheese, and previously cooked onions with garlic and chili flakes. Season everything with sea salt, freshly ground black pepper, and oregano; combine well, using hands. Form 14 even meatballs.
Heat the same non-stick skillet over a medium-high heat again and add extra olive oil. When hot, add the meatballs and cook for 6-9 minutes, rotating every 2-3 minutes or until golden brown on each side. Then, add the marinara sauce and bring to a light simmer. Cook for 5 minutes.
After, remove from the heat and transfer the meatballs with sauce into a 7x10-inch (18x25cm) baking dish (if you used an oven-safe non-stick skillet, you can bake it in that!). Bake for 15-20 minutes or until bubbly. Then, sprinkle grated parmesan cheese and bake for an additional 3-5 minutes or until the cheese has melted.
When done, remove from the oven, garnish with freshly chopped cilantro, and serve!