In a small bowl, whisk together the ingredients for the sauce and set aside or chill until ready to use. In a separate bowl, combine the rolled oats and milk. Let the oats absorb the milk for about 30 minutes to an hour.
In a large bowl, throughly combine the mutton/lamb and chorizo. Season with salt and pepper to taste. Let rest at room temperature.
Heat 1-2 tablespoons of olive oil in a skillet over medium high heat. Saute the mushrooms, onions, peppers, tomato paste and garlic until tender and fragrant, about 5-10 minutes. Season with salt and pepper then remove from the heat and let cool until no longer steaming.
Preheat the oven to 375 F. Add the sauted vegetables to the bowl with the mixture of lamb and chorizo. Stir in the balsamic, eggs, coriander and cumin. Stir in the milk soaked oats until completely combined. Season with salt and pepper once more.
Transfer the meat mixture to a loaf pan. Use a spatula to spread the meat into a smooth, even layer. Press the top into a small mound that tapers at the edges (how a loaf of bread would look).
Pour about half of the sauce over the top of the meatloaf in and even layer. Bake for about 20 minutes then add another 2-3 tablespoons of the sauce. Continue to cook another 15-20 minutes, until the center of the meatloaf reads 160 F on a meat thermometer.
Remove the meatloaf from the oven and let rest for at least 15-20 minutes prior to cutting for best results. Pour the remaining sauce over the top of the meatloaf. Serve with blackened bread and onions in gravy. Enjoy!