Preheat your oven to 375°F (190°C) and line a small baking sheet or loaf pan with parchment paper.
Finely dice the yellow onion and mince the garlic clove until very small.
In a medium mixing bowl, combine the lean ground beef, egg, almond flour, diced onion, minced garlic, sea salt, black pepper, and dried oregano.
Use your hands to gently mix the ingredients until just combined, being careful not to overwork the meat which can make it tough.
Shape the mixture into a uniform rectangular loaf and place it on the prepared baking sheet.
In a small ramekin, whisk together the tomato paste, maple syrup, and apple cider vinegar to create the glaze.
Brush the glaze evenly over the top and sides of the meatloaf.
Bake for 35 to 40 minutes, or until the internal temperature reaches 160°F.
Allow the meatloaf to rest for 5 minutes before slicing to ensure it stays moist and holds its shape.