Preheat your oven to 375°F and line a small loaf pan or rimmed baking sheet with parchment paper.
Finely dice the yellow onion and finely grate the carrot to ensure they blend seamlessly into the meat.
In a large mixing bowl, combine the ground beef, egg, quick oats, diced onion, grated carrot, sea salt, black pepper, garlic powder, and dried oregano.
Gently mix the ingredients by hand until just combined, taking care not to overwork the meat which can make it tough.
Shape the mixture into a uniform loaf and place it into the prepared pan or onto the baking sheet.
In a small bowl, whisk together the tomato paste, maple syrup, and apple cider vinegar until smooth to create the savory glaze.
Spread the glaze evenly over the top and sides of the meatloaf using a spoon or pastry brush.
Bake for 35-40 minutes or until the internal temperature reaches 160°F, then let it rest for 5 minutes before slicing.